Unexpected glowlight danio spawn!

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Lycanthi

Aquarium Advice Apprentice
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Feb 19, 2024
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So I bought 5 new glowlights (well actually 4, one was an imposter - a Celestichthys erythromicron that was in the glowlight tank at the store) 2 days ago, and yesterday while doing a water change, I noticed eggs under the moss. They spawned in the quarantine tank! I wasn't expecting it or prepared for it.

I siphoned them up and put them in a HOB breeder box attached to the QT. I've started an infusoria culture but I doubt it will be ready in time for them when (if) they hatch. Is there something else I can feed them? Will egg yolk work?

Do I need to do anything special to help them hatch? I wasn't sure if they were light sensitive like tetras, but I covered the breeder box with black paper anyway, just in case. The tank temp is around 22 - 23 C - does it need to be raised up for the fry to hatch?

The eggs have gone from fully transparent last night, to transparent with a tiny white circular / bean shape in the centre (the developing embryo?) this morning. Does that sound right or are they unfertilized eggs?

I'm hoping at least a few hatch so I can give raising the fry a go. I've only ever bred guppies or Kribensis cichlids before, both of which have fairly large fry that didn't need special fry foods (I fed the kribs pulverised egg yolk but the parents would also chew up flakes for them).

Attached a photo of the eggs in the breeder box from last night.20240309_232449.jpg

Thanks in advance for any advice or tips.
 
So I bought 5 new glowlights (well actually 4, one was an imposter - a Celestichthys erythromicron that was in the glowlight tank at the store) 2 days ago, and yesterday while doing a water change, I noticed eggs under the moss. They spawned in the quarantine tank! I wasn't expecting it or prepared for it.

I siphoned them up and put them in a HOB breeder box attached to the QT. I've started an infusoria culture but I doubt it will be ready in time for them when (if) they hatch. Is there something else I can feed them? Will egg yolk work?

Do I need to do anything special to help them hatch? I wasn't sure if they were light sensitive like tetras, but I covered the breeder box with black paper anyway, just in case. The tank temp is around 22 - 23 C - does it need to be raised up for the fry to hatch?

The eggs have gone from fully transparent last night, to transparent with a tiny white circular / bean shape in the centre (the developing embryo?) this morning. Does that sound right or are they unfertilized eggs?

I'm hoping at least a few hatch so I can give raising the fry a go. I've only ever bred guppies or Kribensis cichlids before, both of which have fairly large fry that didn't need special fry foods (I fed the kribs pulverised egg yolk but the parents would also chew up flakes for them).

Attached a photo of the eggs in the breeder box from last night.View attachment 389624

Thanks in advance for any advice or tips.
Usually if the eggs are unfertilized, they will turn totally white so if you only see a little dot and it does not take over the egg in 24 hours, you should have some fertilized eggs. Anytime there is a water change, it helps induce fish to spawn so that is probably what happened in your case. Make sure you have an airstone in the container to aerate the eggs and keep things from settling on them. As for food, hard boiled egg yolk mashed through a handkerchief will help get them along but there is a food called liquifry #1 which is also a good starter food for small egglaying fish. (y)
 
Usually if the eggs are unfertilized, they will turn totally white so if you only see a little dot and it does not take over the egg in 24 hours, you should have some fertilized eggs. Anytime there is a water change, it helps induce fish to spawn so that is probably what happened in your case. Make sure you have an airstone in the container to aerate the eggs and keep things from settling on them. As for food, hard boiled egg yolk mashed through a handkerchief will help get them along but there is a food called liquifry #1 which is also a good starter food for small egglaying fish. (y)
Thanks! I'll look for liquifry at the pet shop if they hatch.

The breeder box is one that hangs outside the tank and has flow through from the main tank powered by an airstone so there's constant movement of aerated water over the eggs (can see them wafting to and fro in the tiny current it creates). I did notice a few eggs turn entirely white and start growing a fungus this evening so I took those ones out. There's still a few that are entirely transparent too (it's hard to see if an embryo is growing in those ones).

The white part on the other ones is definitely an embryo (its shaped like a fat comma with a clear head and tail region), I can't figure out if they're alive or dead though. I suppose I have to wait and see if they develop.

Thanks for your help!

Attached photos of a couple of the translucent eggs with white centres,20240311_003342.jpg20240311_005852.jpg and a photo of a clump of eggs with a totally clear egg in the centre.20240311_005940.jpg
 
Today a few of the eggs were totally white and fuzzy with the beginning of mould. I tried to remove them all but only got halfway before I realized the clear eggs have hatched!

The eggs that had a white spot in the middle have turned more cloudy and didnt hatch, so I can only assume those embryos died at some point in development and that's why they went white. I expect they will start to grow a fungus too so I should probably remove them all, correct?

There's about 3 or 4 teeny tiny fry (wigglers?). They are lying motionless on the bottom of the breeder box but they wiggle a bit if I tap the box. If they survive I suppose they will become free swimming within 2 days and only then will need to start eating?
20240311_214048.jpg20240311_214116.jpg

I'm not sure why most of the eggs died, maybe it has something to do with having been shipped, stuck in a tiny pet store tank, bagged up, driven for an hour, then acclimated to different tank conditions over the last couple of weeks? The stress could have harmed egg quality? Or maybe there was an ammonia or nitrite spike due to the tank not being mature (I used a seeded filter but only seeded the sponge for 10 days in my MT). Either way hopefully I can raise the survivors to adult fish.
 
There's also the possibility that the female laid the eggs before the male(s) realized it so they only got in at the last minute. It's also rare that there is a 100% hatch rate on fish eggs.
All the other things you mentioned are also a possibility but less likely when there are successfully hatched eggs.

The fry of smaller species of fish tend to not move a lot as they are trying not to attract attention to themselves. Larger species where the parents usually tend to the eggs and fry, the fry are very active to keep the parent's attention on them.

At this point, yes, no need to feed them until they become free swimming as they are currently absorbing their yolk sacs. You do need to get food ready however as the fry will need food relatively quickly. Unlike larger specie's fry, small species of fish tend to use up the energy from the yolk sac rather quickly. If you don't have any kind of infusoria or the liquifry, add lots of live frilly plants as they tend to also have cultures of infusoria on them that the fry can eat in the meantime. (y)
 
Hmm... I think they were definitely fertilized, I'm almost certain the white bean / comma shape inside each egg was an embryo - that cannot have formed without fertilisation. If it was an unfertile egg it should have just had a circular yolk sac inside the egg?

There were a few (maybe 4 or 5) unfertilized eggs that went white within a few hours after I first collected the eggs, but those went solidly white.

In any case, I think 4 fry have survived so far. My infusoria culture probably won't be ready in time, so tomorrow morning I'll put a clump of java moss in there from my main tank. Hopefully that will last them a day or two? I'll also look for liquifry tomorrow in the lfs.

Thanks for the advice ? fingers crossed I can keep these guys alive ?
 
Hmm... I think they were definitely fertilized, I'm almost certain the white bean / comma shape inside each egg was an embryo - that cannot have formed without fertilisation. If it was an unfertile egg it should have just had a circular yolk sac inside the egg?

There were a few (maybe 4 or 5) unfertilized eggs that went white within a few hours after I first collected the eggs, but those went solidly white.

In any case, I think 4 fry have survived so far. My infusoria culture probably won't be ready in time, so tomorrow morning I'll put a clump of java moss in there from my main tank. Hopefully that will last them a day or two? I'll also look for liquifry tomorrow in the lfs.

Thanks for the advice ? fingers crossed I can keep these guys alive ?
I thought we were talking about possibilities? Obviously they were not spawned under the best of conditions so anything is truly possible. The sperm could have been weak from lack of good conditioning. The egg could have been weak for the same reason. In nature, only 10% ( +/- ) of a spawn grows up to become breeding adults. Deaths come from poor genetics, predation, environmental issues as well as other causes. As a home breeder, the only part we really have control over is the predation part and partial control over the genetics ( over time). So you will never get a 100% survival rate.
What you can/should do with this spawn is learn what to do and not to do. Granted there aren't really enough fry to overcome mishaps but now that you know there are fertile breeders in your tank, you can do proper husbandry to make sure the next spawns have a better chance of success ( should you want to try again) . (y)
 
Yes, I definitely didn't expect them to spawn so soon under such conditions - I was going to try to spawn them in the display tank when they'd finished quarantine. I thought they'd need at least a few weeks to settle in before they felt ready.

With only 4 wigglers I'll be really pleased if I can even get one to reach maturity :) I'm going to treat it like a trial run and learn as much as possible as I've never spawned egg scatterers before.

Hopefully later on I can get them to spawn when I want them to and I'm prepared for the fry!

Right now the male is chasing females around the tank and into the moss and they're wriggling right into the moss and kind of shimmying against each other - spawning again? The females don't look that fat though, they can't have many eggs left. I can't see any eggs being released but I suppose it would be hard to see them even if they were. I guess I'll have to look under the moss again later on.

The wrigglers are jumping off the bottom of the breeder box, doing quick little dashes, and falling back down again, will they continue to do that until they grow a swim bladder and are able to float in the water column?
 
Yes, I definitely didn't expect them to spawn so soon under such conditions - I was going to try to spawn them in the display tank when they'd finished quarantine. I thought they'd need at least a few weeks to settle in before they felt ready.

With only 4 wigglers I'll be really pleased if I can even get one to reach maturity :) I'm going to treat it like a trial run and learn as much as possible as I've never spawned egg scatterers before.

Hopefully later on I can get them to spawn when I want them to and I'm prepared for the fry!

Right now the male is chasing females around the tank and into the moss and they're wriggling right into the moss and kind of shimmying against each other - spawning again? The females don't look that fat though, they can't have many eggs left. I can't see any eggs being released but I suppose it would be hard to see them even if they were. I guess I'll have to look under the moss again later on.

The wrigglers are jumping off the bottom of the breeder box, doing quick little dashes, and falling back down again, will they continue to do that until they grow a swim bladder and are able to float in the water column?
What you are watching with the adults IS spawning behavior. What that means is that whoever was caring for them before you got them, was doing a good job. (y) Sometimes you get lucky and when in a school, the male(s) can spawn with different females all at the same time. That said, it doesn't always happen that way. You can get a reluctant female that doesn't spawn with all the others but the females release a hormone into the water when they spawn that can get another female " in the mood" faster than if she was by herself. These are one of the species that commercial breeders spawn in mass vs pairs only. I like to spawn Danios in pairs or trios in a specially set up tank to ensure that more eggs get protected from the breeders than get eaten.

As for the fry, fry " wigglers" are going to do a lot of different things as they mature. Some of it is testing their fins, some needing to move, some scratching an itch, some is that they are fry and don't know any better. ;) LOL They will get up and swim when they are good and ready. ;) (y) Just don't be in a hurry to get them into the main tank. They need to be much bigger than the mouths of your other fish before they are safe to put in there.
 
Good to know that the pet store I got them from must have had good tank parameters. Their tanks do always look clean and usually have no sick looking fish. The tank the glowlights were in was tiny though, smaller than my QT, bare bottomed, and crammed with fish. They were in the "nano aquarium" section of the store but I don't think I'd consider C. choprae to be a nano fish, too fast and active even though they are small.

I've never really properly seen wigglers before, my kribs had fry several times but each time I never saw them until they brought them out of the cave when they were free swimming. At that stage they are so much more developed than these teensy little things. These guys look more like bug larvae than fish. I always just left the fry with the parents with my kribs, not all of them reach adulthood that way but that was a good thing or my tanks would soon have been overrun.
 
Good to know that the pet store I got them from must have had good tank parameters. Their tanks do always look clean and usually have no sick looking fish. The tank the glowlights were in was tiny though, smaller than my QT, bare bottomed, and crammed with fish. They were in the "nano aquarium" section of the store but I don't think I'd consider C. choprae to be a nano fish, too fast and active even though they are small.

I've never really properly seen wigglers before, my kribs had fry several times but each time I never saw them until they brought them out of the cave when they were free swimming. At that stage they are so much more developed than these teensy little things. These guys look more like bug larvae than fish. I always just left the fry with the parents with my kribs, not all of them reach adulthood that way but that was a good thing or my tanks would soon have been overrun.
Yeah, cichlid fry are very different from Danio fry. When I was breeding Zebra Danios, the fry would emerge from the marble covered floor and attach themselves to the tank sides. The fry were transparent so it looked like a whole bunch of eyes sticking to the glass. LOL
 
Today I managed to recover more eggs, I think they're spawning almost every day now. There were less eggs this time, but more of them were transparent (I recovered 10 and put them in the breeder box).

I think they were laid late yesterday evening because I saw some intense spawning activity at that time and I thought I could see eggs being released (I could see something falling through the moss anyway). Some of the eggs appear to stick to the moss and some aren't sticky. A little bit odd since they're supposed to lay non adhesive eggs.

Do they just spawn every day? If so I'll have to stop recovering the eggs at some point or I won't have space to grow them out.

The 4 original fry are still lying on the bottom or occasionally clinging to the sides of the tank. Still not exactly free swimming but they can swim better now when disturbed or spooked. They don't appear to be eating anything yet.
 
Today I managed to recover more eggs, I think they're spawning almost every day now. There were less eggs this time, but more of them were transparent (I recovered 10 and put them in the breeder box).

I think they were laid late yesterday evening because I saw some intense spawning activity at that time and I thought I could see eggs being released (I could see something falling through the moss anyway). Some of the eggs appear to stick to the moss and some aren't sticky. A little bit odd since they're supposed to lay non adhesive eggs.

Do they just spawn every day? If so I'll have to stop recovering the eggs at some point or I won't have space to grow them out.

The 4 original fry are still lying on the bottom or occasionally clinging to the sides of the tank. Still not exactly free swimming but they can swim better now when disturbed or spooked. They don't appear to be eating anything yet.
Once they become free swimming, they won't be attaching to the sides anymore. They won't eat until they reach that point.
I've not had the glo-lite Danios before but the other danios I've spawned were a " one and done" spawners and from what I've read about the glo-lites, they usually only spawn once every 7-10 days. The eggs should not be very sticky but that doesn't mean that what they hit after the spawn doesn't have a film over it that can make the eggs stick to it. You may want to keep harvesting the eggs for a while since the breeders only live for a few years so you may be losing them at any time. By creating your own school of the next generation, you'll know how old they actually are so you'll know when to start harvesting their eggs for their next generation. (y)
 
Once they become free swimming, they won't be attaching to the sides anymore. They won't eat until they reach that point.
I've not had the glo-lite Danios before but the other danios I've spawned were a " one and done" spawners and from what I've read about the glo-lites, they usually only spawn once every 7-10 days. The eggs should not be very sticky but that doesn't mean that what they hit after the spawn doesn't have a film over it that can make the eggs stick to it. You may want to keep harvesting the eggs for a while since the breeders only live for a few years so you may be losing them at any time. By creating your own school of the next generation, you'll know how old they actually are so you'll know when to start harvesting their eggs for their next generation. (y)
Oh wow I didn't realize they had such short lifespans! I sort of just expected them to live for 4 or 5 years like most tropical fish. I've just looked it up and they only live from 1-3 years.

I'll try to get as many eggs as possible then since not all the fry are likely to survive anyway.

I'm pretty sure now that I have 1 male and 3 females in this group in quarantine. I think he's probably spawning with a different female each day and the others are recovering in between. I've just noticed more eggs so they spawned again today. It seems to be every 2 days for these guys (the male is a really busy fellow it seems).

The trio in my display tank don't seem to spawn. Im pretty sure that group is 2 females and 1 male but the male is a bit of a runt compared to the male in the QT group so maybe the females aren't as interested in him? I occasionally see him chasing them but I've never witnessed the "shimmy" in the moss behaviour in those 3.
 
Oh wow I didn't realize they had such short lifespans! I sort of just expected them to live for 4 or 5 years like most tropical fish. I've just looked it up and they only live from 1-3 years.

I'll try to get as many eggs as possible then since not all the fry are likely to survive anyway.

I'm pretty sure now that I have 1 male and 3 females in this group in quarantine. I think he's probably spawning with a different female each day and the others are recovering in between. I've just noticed more eggs so they spawned again today. It seems to be every 2 days for these guys (the male is a really busy fellow it seems).

The trio in my display tank don't seem to spawn. Im pretty sure that group is 2 females and 1 male but the male is a bit of a runt compared to the male in the QT group so maybe the females aren't as interested in him? I occasionally see him chasing them but I've never witnessed the "shimmy" in the moss behaviour in those 3.
Regarding your other male, it could be his size, it could be he's too young or it could be their diet is not the best to get them into spawning condition. While it's always nice to think you had something to do with new fish spawning in your tank, it was really most of the work done for them before you got them that is why. The real secret is their second spawn. THAT is all on you. ;) (y) A water change ques most fish species to spawn which is why new fish spawn when they get to your home. (y)
There are many fish with shorter and longer life spans in a tank than these fish. 4-5 years is not really even a good/ accurate average. Good husbandry usually rewards you with fish living longer than they would out in the wild. Age in a fish tank is hard to really pinpoint because there are so many variables as to why fish die in a tank. :( Regarding your fish, you don't really know how old they were when you got them which is why you should take advantage of these spawns to make sure you keep a school of these going. (y) 10 or 20 years from now, you can point to your school of Glo-lite Danios and tell people " Yeah, I have these because I bred their great, great,great,great,great,great,great,great,great,great,great,great,great,great,great, great grandparents. " ;) ;) (y)
 
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Half of the eggs I recovered yesterday hatched. They seem to be hatching early for some reason (they don't look fully developed). I read that zebra danios do this if chemicals from crushed embryos are in the water, so possibly the adult fish predating on eggs in the QT (which the breeder box is attached to) is causing them to hatch out early. That or me siphoning them up and moving them is disturbing them enough to think a predator is eating them and they hatch shortly afterwards to escape it.

I found another batch of eggs today under the moss. Only about 5 transparent ones and 5 white centered ones. I moved the transparent ones to the breeder box. The celestichthys erythromicron was also under the moss poking around (probably eating eggs or newly hatched fry).

I also found one free swimming fry in the QT and quickly scooped it up and put it in the breeder box. I don't know if it was in the moss and was disturbed out of hiding when I siphoned up the eggs, or it was somehow swept out of the breeder box when I was moving eggs into it.

20240316_225803.jpg

I can't tell if it's finding anything to eat - there's some moss and guppy grass in the box with them. Should I try to feed egg yolk or will that foul the water?
 
Regarding your other male, it could be his size, it could be he's too young or it could be their diet is not the best to get them into spawning condition. While it's always nice to think you had something to do with new fish spawning in your tank, it was really most of the work done for them before you got them that is why. The real secret is their second spawn. THAT is all on you. ;) (y) A water change ques more fish species to spawn which is why new fish spawn when they get to your home. (y)
There are many fish with shorter and longer life spans in a tank than these fish. 4-5 years is not really even a good/ accurate average. Good husbandry usually rewards you with fish living longer than they would out in the wild. Age in a fish tank is hard to really pinpoint because there are so many variables as to why fish die in a tank. :( Regarding your fish, you don't really know how old they were when you got them which is why you should take advantage of these spawns to make sure you keep a school of these going. (y) 10 or 20 years from now, you can point to your school of Glo-lite Danios and tell people " Yeah, I have these because I bred their great, great,great,great,great,great,great,great,great,great,great,great,great,great,great, great grandparents. " ;) ;) (y)
It would be great if I can get them to adulthood and spawn the next generation! Sounds like a really fun and rewarding project.

They've spawned at least 3 times since I've had them in the QT. I'm wondering when (if) it will ever stop? Its great that they feel healthy enough to spawn but I'm starting to worry that the females will be worn out by it. They'll have more space to hide from the male in the display at least.

The original 3 I got were from the same shop, also spent time in the same QT before being moved, but acted very differently (lots of hiding and no spawning activity in the QT). Maybe 3 fish isn't enough for them to feel like a shoal? I notice that the 2 that look like females seem to hang out together and the male is always at the other end of the tank.

Maybe I'm wrong and one of the "females" is actually a fat male and these 2 paired up? (do C. choprae do that?).

Anyway, even if they did spawn in the display I doubt I'd ever see any fry survive there since the barb is constantly picking at the moss for food. He would definitely vacuum up any eggs or fry.
 
It would be great if I can get them to adulthood and spawn the next generation! Sounds like a really fun and rewarding project.

They've spawned at least 3 times since I've had them in the QT. I'm wondering when (if) it will ever stop? Its great that they feel healthy enough to spawn but I'm starting to worry that the females will be worn out by it. They'll have more space to hide from the male in the display at least.

The original 3 I got were from the same shop, also spent time in the same QT before being moved, but acted very differently (lots of hiding and no spawning activity in the QT). Maybe 3 fish isn't enough for them to feel like a shoal? I notice that the 2 that look like females seem to hang out together and the male is always at the other end of the tank.

Maybe I'm wrong and one of the "females" is actually a fat male and these 2 paired up? (do C. choprae do that?).

Anyway, even if they did spawn in the display I doubt I'd ever see any fry survive there since the barb is constantly picking at the moss for food. He would definitely vacuum up any eggs or fry.
Danios usually will pair off from the school to spawn but they do not stay together as a pair after that. ( Same with Barbs, Rasboras and Tetras or any egg scatterer.)
As for them spawning 3 times, if you have 3 females, it's more likely you had 3 spawns from 3 different females. Spawn #4 would then be from you. ;) (y)
Once the fry are free swimming, they should have a seasoned sponge filter in their tank to help provide filtration as well as another food source. ( Microbes on the sponge filter can become food. ) Usually all the fry will become free swimming within a day or so. This is why you don't really want to put multiple spawns together unless they occur on the same day.
You may not see any food in the stomachs if the fry are eating infusoria but you will see yellow in the stomachs when they eat the egg yolk and orange in their bellies when they start earing brine shrimp nuplii ( or whatever color food you are feeding the fry. ) Yes, fry foods are going to foul the water if overfed or not eaten so you will be needing to do cleaning and water changes on the fry tanks.
 
All 4 fry are free swimming as of yesterday morning.

I can't see any of the ones that hatched from subsequent batches but the bottom of the breeder box is quite dirty now so they may have perished or they might still be down there.

How long can free swimming fry survive without eating? I can't tell if they're eating anything - there's no obvious belly (I can see their eyes and their swim bladder but not much else). I've tried to feed them various things, including egg yolk, mashed flake, and the water squeezed out of my display tank's sponge (I was hoping it would contain some infusoria). They still just perform the same jerky, swimming movement and dont really seem to be searching for food.

There are a bunch of tiny critters moving around near the bottom of the breeder box ( I can see them if I shine a light across the bottom) but even those might be too large for the fry, and the fry don't seem to go down towards the bottom anyway (they hover just under the surface most of the time). I expected them to pick at critters on the moss but they don't do that either.

They're giving me anxiety lol.

The first infusoria culture I started seems to have grown yeast (it was bubbling and frothing a lot) and smells kind of fermented so I don't think I should use it (ethanol can't be good for fry) - I can't see any infusoria in it either, although it did go kind of green.

The second still isn't ready to be used (hasn't cleared up yet).

I fed them filter water and egg yolk this morning. I also noticed the glowlights have spawned again and 2 of the females look fat again. I left the eggs where they were as they'll probably just get fungus in the breeder box.

Yesterday I noticed small white egg like things stuck to the moss, about half the size of the glowlight eggs. Could the C. erythromicron also be spawning with the choprae male? I'm pretty sure the C. erythromicron is a female - the male choprae chases her along with the other females. None of the eggs (if thats what they were) were fertile anyway, I'm pretty sure these species can't hybridise. In any case I left them in the tank and I can't see them now so they probably got eaten, whatever they were.
 
Pictures of the fry from last night:
20240318_144457.jpg20240318_145923.jpg20240318_144326.jpg

And one I took of the first free swimmer 2 nights ago:
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