Every single fry is dying.

[confused_aquarist]

For the past few months, I've been breeding Norman lampeyes, clown killies, and A. cognatum, and maybe it's beginner's luck, but out of 50 or so fry I raised I hadn't lost a single one. It changed a month ago, and now I have really taken things to extreme, every single fry dies a day or two after hatching and it's happening to all 4 of my tanks.

The ones from previous hatches are doing just fine. The only thing that has changed, I think, is I've started feeding fish chlorella instead of spirulina because when I grow BBS in chlorella the water stays cleaner. Also I guess another thing is the water has become crystal clear because the tank becoming mature. I do filter maintenance every 3 months and there are no detectable changes in water parameter.

The fry seem to struggle to stay afloat, and not a single one ever starts eating. Sometimes a few hours after they die their head seems to explode, not sure if it's popeye. Just wondering what the possibilities are.

I'm hatching the eggs at 23 degrees in paper cups with 2 inches of water from main tanks. Hatch rate is near 100%.

 

[Colin_T]

There is either something wrong with the water or the fry are starving. However, if they are dying within a few hours of hatching it's normally related to water. I had the same issues years ago when i was breeding rainbowfish. The eggs developed and hatched and the fry died within minutes of hatching. It turned out the water company had been putting in 3.5 times the safe level of chlorine into the water supply. So even though I was dechlorinating water and letting it stand for a few days, there was still chlorine in it. There is also something else in our water supply that leaves a white residue after the water evaporates. It's not calcium or any mineral I can test for and it sets hard.
You need to check the tap water and tank water for everything.

Filters should be cleaned at least once a month. Don't replace filter media/ materials, just wash/ squeeze them out in a bucket of tank water and re-use the media. tip the bucket of dirty water on the lawn/ garden outside.

Make sure you gravel clean the substrate every week to keep it clean.

If you are feeding fry with green water, the water needs to be green and you need aeration in the tank but no filter otherwise the filter sucks up the algae. If you are culturing algae, make sure there isn't any plant fertiliser in the water because that will kill fish very quickly.

Make sure the water temperature is correct, it should be if the eggs are hatching but check anyway.

I used to wash out rearing tanks after every batch.

 

[confused_aquarist]

There is either something wrong with the water or the fry are starving. However, if they are dying within a few hours of hatching it's normally related to water.

It's strange since you mentioned that filter needs to be maintained every month, I used to do maintenance every month but switched to every 3 months because others have told me it's BAD to clean it too often. For me though I don't really see much difference whether I do it every month or 3 months. I'll switch back to doing monthly maintenance just in case though.

I think the issue might have to do with either chlorine or PFAS in the area. It turned out that the filter cartridge we use to run tap has expired for a year. I've never had to think about filter cartridges since I never had to use them.

 

[seangee]

I discovered that our local water supplier chlorinates the reservoir every Friday because residential demand peaks over weekends. Knowing this I discovered that the chlorine in the tap water does actually smell stronger on weekends. For this reason I only ever top up the fish pond on a Thursday when the concentration is lowest. It may be worth checking if they have a specific day.

 

[confused_aquarist]

I discovered that our local water supplier chlorinates the reservoir every Friday because residential demand peaks over weekends. Knowing this I discovered that the chlorine in the tap water does actually smell stronger on weekends. For this reason I only ever top up the fish pond on a Thursday when the concentration is lowest. It may be worth checking if they have a specific day.

That's awfully interesting. Our tap water does sometimes have a strange smell (sort of like nasty plumb piping smell), though I'm not sure if that's chlorine smell. It's rare, but there may be some other things in there that I can't smell. It's very expensive to have water tested where I live, so I'm going to just see if the new cartridge will fix the issue. It's strange because all of the fry would swim up to the surface for a while (they have to wiggle in order to stay afloat), then sink to the bottom. I'm not sure if that's because they're tired or due to swim bladder issue. They would never start eating, not a single one of them. I've been breeding them nonstop and haven't seen a problem like this.

 

[GaryE]

In killie breeding circles, they're called belly sliders. Why it happens is debated, because it strikes in different conditions. Usually, it's blamed on hatching issues - if the fish is too long in the egg (often the mineral content of the water hardening the shell), or hatching in low oxygen conditions. It's a real problem for annual killie keepers.
I've had a few scattered fry hit with it, and it's less common with the types of killies you're breeding. But because it hasn't been an issue with my Aphyosemion, Epiplatys and lampeyes, I haven't dug into it. I've raised thousands of killies by now, and seen maybe 30 bellysliders in that time. Most have come from eggs I bought and that survived trips through the international mail system.

I've read and heard discussions involving serious, respected scientists who use Nothobranchius for research discussing this, and no one has found one single answer to why. It seems the swim bladders aren't properly inflating after hatching, but what's doing that may be a bunch of different causes.

 

[confused_aquarist]

In killie breeding circles, they're called belly sliders.

In the previous hatch of A. cognatum, I had 1 true belly slider, actually because the fry are transparent I can easily see that he doesn’t have a swim bladder and is bent slightly upwards compared to others, probably due to the lack of swim bladder where there’s supposed to be. There’s probably a degenerate one somewhere else but I can’t see it.

Actually, for me the aphyosemion are all born as belly sliders. It takes them 1-5 days to become free-swimming and up to a week to start eating. These seem perfectly fine. Not sure if that is standard.

 

[GaryE]

That is odd. I've bred two different locations of cognatum, and while they cruise the bottom to start, they don't slide or hop. Still, if they are developing normally afterwards, it may just be the hatching container. I use 2.5 gallon/9.5 litre tanks for hatching out, and don't start them individually.

 

[confused_aquarist]

That is odd. I've bred two different locations of cognatum, and while they cruise the bottom to start, they don't slide or hop. Still, if they are developing normally afterwards, it may just be the hatching container. I use 2.5 gallon/9.5 litre tanks for hatching out, and don't start them individually.

That's interesting. Mine would just lay on the bottom for days and I have to move them to check if they're still alive. They're always near the surface after they start to swim, but they all gather to the bottom if I put in a piece of mop. They're from ”Mai-Ndombe" location. I was hatching those in 4 inch satellite containers with water drip so there definitely seem to be a lot of tiny air bubbles in the water. The tank literally has just water and a sponge. So many mysterious issues...

 

[GaryE]

Mai-Ndombe is a lake in the Democratic Republic of Congo. It's blackwater, very blackwater, with a pH of around 5. I've bred one of the Cichlids from there, wild caughts, and they needed extremely soft water (but were good at pH 6.5). Your fish are likely from the river feeding in, and I have never been able to get info on that habitat.
I still have hopes of going there someday, as there is a slight chance of that. But hopes don't provide data.

You have the ones that hatched from before the problem developed, so it isn't a crisis. Has the room temperature changed seasonally? It could be that simple.

I used to get Aphyosemion polli, cognatum and elegans types regularly as mixers in Congo shipments, or in small numbers when I helped out with importing. I rarely collected eggs as in planted tanks, they built up large colonies very quickly. The elegans group of Aphyosemions is very beautiful. I've never seen the Mai Ndombe ones though. You're lucky.

 

[confused_aquarist]

Mai-Ndombe is a lake in the Democratic Republic of Congo.

Well, mine probably aren't the most beautiful (the picture quality is poor too). They're actually "Nioki Mai-Ndombe", so they do probably come from a river in that town. Actually, I almost thought that this is a mistake because the pair looks a lot more like the A. christyi that appear on google searches! The male is has bright yellow fin and red dots on scales and fin. The female is orange with a lot of black dots looking almost black. It's very easy to sex the fry because they're either yellow or black.

Actually I think the fry are hatching out prematurely, all of them. They have very huge yolk-sacs even though they take 3 weeks to hatch, almost like they no longer want to stay in because otherwise they'd be in there for too long. Not sure if this is pH affecting development or nutrition issues. I feed the parents very small portions so it could be malnourishment now that I think about it (usually, I can find at most 3 eggs a day). The ones that hatch out spontaneously in the tank seem to just starve because of lack of infusoria.

 

[GaryE]

I have always found A. christyi, cognatum and polli really hard to differentiate.

3 weeks is very slow. All of mine have been very close to 14-15 days, no matter which elegans group species. I feed tanks as if there are fry. Adults can eat tiny food, and freshly hatched brine shrimp is a staple here. The fry don't need microscopic foods - as soon as they are swimming they seem able to take artemia naupli.

3 eggs a day is pretty standard - quite good actually. Your portions must be excellent.

There's never one "recipe" for this kind of fish. They're always trial and error at first, because we keep them differently.

 

[Innesfan]

I have always found A. christyi, cognatum and polli really hard to differentiate.

Yes! And it seems to have shifted over the years. When I was a kid and A. cognatum first became available, it was basically a two-color fish--carmine dots and fin borders over a neutral body tone.. The edges of the caudal were parallel to each other and some fins were tipped white. I've not seen that form in decades, Subsequent importations presented a fish with lots of yellow on it and the caudal was more flared. I think I like A. sp. Lobaye as much as I do because it reminds me of the 'original' cognatum.

 

[GaryE]

This came in at one point, and seems to have been Aphyosemion polli.