Fry growth questions

I've noticed that some of my chitande masinje fry are randomly dying off. All the parameters are fine, and I do regular water changes. Is anything wrong?

Also, I've noticed one of my one month old Saulosi seems to have either very small, undeveloped eyes or no eyes at all.

Not sure about the die off, but I have noticed with many of the species that I have bred that some fry are just weaker than others. 100% survival rate in nature is impossible, so the weaker usually don't make it. I've never had fish with no eyes, but I have had fish from spawns with weird gill plates and incomplete fins. Sometimes you just need to cull them.

I've had an Oyopharynx lithobates fry hatch with only one eye. It also had a lot of other skull deformities as well so although it made it a few weeks, it didn't survive much more than that.

My most recent group of lithobates is the only group I've ever noticed that had some die off. Only five or six out of 60+ fry have died but the cause is unknown. Its very hard to diagnos a fish That's no bigger than a 1/2". I assume they were just weaker fish that couldn't compete with the fast growers. Lithobates are the smallest fry I get, they are extra tiny and I assume extra fragile compared to fry from say a Taiwan reef that are much bigger. I thought it may have been related to the higher temps during the summer. My tanks get up to the low to mid 80's reducing the amout of oxygen in the summer. Not sure where you would even start trying to treat them if I got to the point where I thought they needed meds I'd probably just use a small amount of a broad range antibiotic like ampicillan, sulfamethazone or metro. The fact that there are visual deformities would make me think there could be other problems that would prevent them from living no matter what you did. I'd get my magnifying glass out to look for things like bent spines or deformities of the mouth and face.

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At the ACA convention in Louisville this year, Willem Heijns provided some really interesting estimates of fry survival rates in nature vs. maintaining a stable population of fish in a given body of water. Well less than 1% make it to reproductive age (lest the lake be overrun with fish in a few years).

His estimates were for substrate-spawning Amphilophines (red devils), which have a lot of babies. I'd assume mouthbrooders (fewer, bigger babies) have higher survival rates but certainly nowhere near 100%.

It's possible to have really high survival rates in captivity but sometimes the ones that die are the ones that wouldn't have made it under tougher conditions.

Or maybe it's something that you're doing. What's your fry-raising set-up?

Matt

For the Saulosi you want to cull that one - a lot easier now rather than later.

More details would help with possible explanations for your chitande masinje losses.

I have my chitande masinje in a 10 gallon, with a sponge filter. I have 2 spawns in there, the second was spit a week after the first. I have about 50 in there right now, down from 70 about a week and a half ago.

What you do with all that fry that survive???


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I wouldn't keep fry from two spawns together. Big ones will pick on the little ones...

How often/how much water do you change?

Matt

npbarca said:

I have my chitande masinje in a 10 gallon, with a sponge filter. I have 2 spawns in there, the second was spit a week after the first. I have about 50 in there right now, down from 70 about a week and a half ago.

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dogofwar said:

I wouldn't keep fry from two spawns together. Big ones will pick on the little ones...

How often/how much water do you change?

Matt

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That's what I thought at first, but it is the bigger ones that are dying. I do 50% every 2-3 days.

This is my first chitande masinje spawn, so once they get bigger they will be up for sale.

Is the sponge mature? When's the last time you rinsed the gunk out of it?

Maybe smaller, more frequent water changes.

Hard to say what's going on but I try to steer away from 10g tanks or smaller for fry because they're tough to maintain consistent water quality, especially with a lot of fish in them.

npbarca said:

That's what I thought at first, but it is the bigger ones that are dying. I do 50% every 2-3 days.

This is my first chitande masinje spawn, so once they get bigger they will be up for sale.

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I'm setting up a dual 20 long growout soon, so hopefully that will help. Sponge is mature, and has been cleaned out about a month ago.

dogofwar said:

Hard to say what's going on but I try to steer away from 10g tanks or smaller for fry because they're tough to maintain consistent water quality, especially with a lot of fish in them.

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+1 Not everyone does this, but my minimum for fry growout is a 20-30 gal tub. Most of the time I use a 50 or 55 gal tank, often divided for different species, different sized fry, etc. Not that this gives you 100% fry survival, which is not realistic for most fish ime, except, for example, something like frontosa, which produce relatively fewer, but also larger and more robust fry than many species.

But part of what I like is the larger tank is less work to maintain optimal conditions, including fewer water changes, and allows you to give fry a more natural, less laboratory-like environment, which I also prefer. Adding a bit of aquascape to a fry tank appears to be better for their brain development. Link