Fry Die - Seeking advice...

[Moose-Dad]

Hello All,

My first post here.

Briefly, I have a dedicated fry tank for my albino cory catfish eggs & fry. I presently have 6 live fry about a month old. They are doing well.

But, I have had one serious die-off, and since then, every egg that has hatched only lives a few hours (less than a day, for sure) before dying.

Let me give you some background. I am NOT an animal specialist. I am a guitar builder and repairman, top level at my trade. Although I am from an academic family and have a decent capacity for understanding, I am super super super out of my element when trying to raise these wonderful little fishies. For example, my 8 year old son knows more species of animal than I do, but he is not a fish specialist, and he is only 8, so he can't really help me out much with my cory fry troubles.

My 2 cory catfish (albino) were luckily a male and female, and one day I thought I had a ring fungus or ring worm on my aquarium glass, but you know what it was - eggs. Since then, I have been successfully transferring the eggs to first a poorly suited tiny tank, then to a 5.5 gallon tank that is (was??) working well.

In my first poorly suited fry tank, after exactly one week, all the eggs hatched. What a joy!! About 48 little critters! They lived well for 2 days, then mass death!! I attribute it to the ill suited filter (a tiny power filter to which I attached a sponge to both the intake and outflow to avoid sucking the critters in). There was poor circulation in the tank, and I could see a fine white buildup at the bottom of the tank, so I expect water quality killed the critters.

(BTW, I CANNOT buy a standard air-driven sponge filter in my area, so hence the jury-rigged filter setup.)

Okay, so in the meantime, my two cory lovers - Cory and Corina - kept laying eggs, and I REALLY love living creatures, and REALLY want to be able to rear these baby fishies, so I bought a 5.5 gallon tank to use as a dedicated fry tank. I bought a "whisper" silent air filter to which I affixed a sponge and had fry hatch and grow. But, when it came time to feed, the filter was poor quality and didn't have enough circulation so I noticed the tank getting dirty and I changed the filter to an external "waterfall" style power filter to which again I attached a sponge to the intake. This filter did me well and I had lots hatch and had about 3 dozen growing happily and beginning to feed.

Now, here again, I get to the point where I am really just shooting in the dark. I cannot get "infusoria" or fry feed here where I am, so I used some algae/fish disks that I would wet in a separate container, then drop little bits into the tank with a turkey baster used as an eye dropper. This worked well, and the critters were doing okay for a couple weeks.

Then, worried about what I am going to do during New Years when I am away for 5 days, I tried dropping the whole disk into the tank to see if it would work as an "auto feeder" but of course, that was idiotic and the disk grew fungus or algae (got fuzzy), and then the tank got dirty (cottony fuzz on the tank walls and some of the rocks on bottom). So, I ditched that idea and got the tank clean again. BUT, due to my tank dirtiness, I lost 30 or more little fry that had been doing a-ok up until this time. Only 6 fry (the biggest) survived, and these are still doing seemingly well after a week or more since the tank got cleaned up.

I now feed the critters VERY sparingly, but more often, so I don't see build up of food particles. I feed them a crushed (powdered) blend of TetraMin's "The Rich Mix" which is what the mommy and daddy eat, mixed with some powdered freeze dried blood worms and algae pellets (I think I'll stop adding the algae pellets, since even the adult cories don't seem to like it as much as the "rich mix"). The tetra min rich mix is good enough to keep all my other tropicals (a few species of tetra) healthy, and it keeps mommy and daddy cories healthy enough to successfully breed, and it is doing fine for my living fry, so I figure it must be okay.

So, all this background to ask a couple questions:

1) What on earth could be going wrong that my fry are just dying now shortly after birth? I really do understand why they died before: specifically, I killed them by not ensuring water quality (filtration troubles first time / overfeeding and damaging water with fungus/mould/algae the second time). Could it be that the fry were damaged during their egg stage in the poor water, and that when they hatched they would die no matter even if the water was perfect???

2) The present substrate I use is a mix of medium size pebbles (enough for the mini-fry to hide in, but little enough that the bigger ones can forage amongst them on the bottom for food) and these medium pebbles are on a black sand (National Geographic brand fine sand. Remember, ALL my fry in my 5.5 g tank were living successfully in this substrate for about a week and a half before the massive die-off, and the 6 that survived are still alive and doing well. One worry I have about this substrate, however, is that it may be too sharp, since the big 6 don't seem to have long barbels, especially the biggest one whose barbels seem to be nearly like stumps. (I did have a problem with a sharp gravel substrate that damaged the barbels of my mommy and daddy long before they started laying, and hence I fully removed the sharp gravel and changed to the medium sized round smooth rocks that is successful now.)

3) The filter I use now has been successful for fry for about a week before I fouled the water with over feeding, but now they just keep dying after hatching. I can't 100% remember if fry successfully were born and survived to the eating stage with this new filter. Maybe the fry were a few days old before I changed to it from the air-driven jury-rigged sponge filter. Perhaps the current is too strong for the new-borns...???

I am REALLY at a loss as to what to do. I REALLY like these critters, and want to be able to return to my successful stage in rearing the fry.

Any advice at all would be GREATLY appreciated. Thanks a million in advance. And sorry for the very long first post.

I can post a photo if this would help.

[syno321]

A photo of the hatching vessel and the rearing tank would be helpful.

[Moose-Dad]

I'll try to post some photos. Busy here at year end. Thanks for the reply! Stay tuned.

[Bwhiskered]

What are you feeding them? They should not be fed until the yolk sac is absorbed. Tbe first food should be micro worms for the first few days to a week.

[Moose-Dad]

Hello,

Again, thanks syno321 and Bwhiskered for your interest and responses. Sorry I am inept at getting a photo posted.

Here is an update...

After several full clutch (is that what you call a batch of fish eggs) deaths, I went away for 4 days and had a friend feed them once a day. Now, the little critters are doing fine and I presently have a clutch of about 3 dozen babies who are 1.5 weeks old. My big 6 are doing okay, and I have 2 in my main tank (doing fine) and 4 in another mini tank doing fine, but looking bored.

So, overfeeding and fouling the water quality was probably the issue. As I mentioned in my first post, I am an overly nervous and cautious sort, but my over-nervousness in this case resulted in over-feeding.

FWIW, I now have an outbreak of planaria. I'll have to buy some "no planaria" to get rid of them. But, maybe either of you can tell me if the little critters like to eat the little planaria. They are, after all, micro worms, and I have heard that the corydoras natural omnivorous diet includes worms. If the worms aren't trouble, which they don't seem to be (and this is what I have read on other sources on the internet), and if the worms can be a food source, then I would guess that as long as I don't over-feed and foul the water, that the planaria could be a benefit.

My present food is a blend of Tetramin "rich mix" granules, Omega One algae/protein granules for "all omnivorous fish", and freeze dried blood worms that I crush into a fine powder. I now feed them about 3 times a day, but VERY very little.

I love these little critters. Never thought it would be so "fun"!

[bekateen]

My present food is a blend of Tetramin "rich mix" granules, Omega One algae/protein granules for "all omnivorous fish", and freeze dried blood worms that I crush into a fine powder. I now feed them about 3 times a day, but VERY very little.

Hi Moose-Dad, Congratulations on all your success spawning the Corys (more accurately, congratulations to your Corys for doing their business frequently, and good for you to get to enjoy the fruits of their labors! ).

As for your choice of fish food, I think that should be fine. I prepare a similar blend of various adult foods for my albino Cory fry: (dry flakes, spirulina wafer, small granules, and some freeze dried shrimp or freeze dried Tubifex worms). I pulverize them into the finest powder I can make using an ordinary kitchen mortal and pestle.

Do you have any live plants in the fry tank? In my albino Cory fry tank I keep a thin layer (1 cm) of playsand for substrate and a big tangle of Java moss. I also add just a few live Tubifex to the tank, which start to live in the sand. I keep this tank running at all times, even when I don't have any eggs or fry, so that if I wake up one day and I find eggs in the parents' tank, I can immediately transfer them into this established fry tank. My suspicion (and my hope) is that the combination of sand and moss creates a supportive environment where infusoria flourish so that there is always some live food for the fry, in case I am unable to feed them for a day. Then, as the fry start to get larger, they begin to eat the live Tubifex worms - it is a laugh to watch a small (about 4mm long) baby Cory try to eat a large Tubifex worm. Often, two Corys will grab the same worm from opposite ends and eat towards the middle where they meet - it's like watching the famous "spaghetti scene" from the Disney movie, "Lady and the Tramp." During the times when I don't have any fry, the tank, and especially the moss, become overrun with microscopic organisms, and when the fry are present, these mostly disappear. I suppose they could be hiding, but I think they're getting eaten too.

One more thing that is worth keeping in mind - Big die-offs like you're experiencing are avoidable, but some deaths will occur naturally, and should be expected. I don't know how many eggs you get at a time, but my big female albino Corys can lay over 200 eggs in one night (I think this is from 2 females together, but I don't keep track), and I just have to figure that some of these eggs are no "good," from a genetic or developmental perspective. A few of these might survive as fish with birth defects (like when you see fish in pet stores with deformed spines or heads), but most will just die along the way. From clutch to clutch, I've had survival rates that varied from as low as zero (total die off) to as high as 90% (after hatching).

Hopefully that helps. Good luck with your Corys!
Cheers, Eric

[bekateen]

By the way, I have never been able to find any microworms for sale locally, but I'm under the impression that my Tubifex worms breed in the sand, and their offspring can substitute for microworms. If I take a turkey baster and use it to churn up the sand when the fry are in the tank (gently of course, without burying the fry), hundreds of tiny (about 2 mm long) worms are released as the sand settles back down in the tank. These worms float in the water column and the fry like to feast on these. To be truthful, I've never inspected these worms under a microscope or isolated them and tried to grow them out, so it's possible that they are some kind of microworm and not juvenile Tubifex - but honestly, I don't care as long as my fish eat them.

[Moose-Dad]

Hey Bekateen,

Thanks for your posts and for sharing your ideas. As soon as I read about 2 corys eating the same worm, I got the same image from the Disney movie then read on to your next sentence!!

Interesting idea about having tubifex worms in the tank at the same time. I have read that live, just hatched baby brine shrimp are great food, too, but the effort required is too much for busy me.

I don't have any moss or plants in the fry tank. I had a few plants that I tried in my main tank, but they gathered too much gunk and the water became fouled so I got rid of them all except for one short sprig that is staying healthy. The plant is one that has "leaves" that almost look like spruce needles. Since I got them (and got rid of most), I read that corys tend to prefer broad leafed plants. So, my bad.

My breeding pair will lay anywhere from 24 eggs or so on a small batch to about 50 on a large batch. I can't imagine 100 eggs coming out of mama all in one night, since the gal isn't so huge (maybe 4.5cm long).

They haven't laid on their most recent cycle, so I am wondering if they are done for this season. If what I read is correct, they breed in autumn...?? These guys started breeding mid october and finished near the start of January. If they never breed again, sure I'll be disappointed, but it has been a great experience for me and my children. Especially my boy (nicknamed Moose, hence my user-name) who has only just turned 8 but is ridiculous in how many animal species he knows. I showed him Crocodile Hunter for the first time today, and Steve took a snake from the water (off Indonesia, if I remember correctly) and my boy stated immediately and correctly what type of water snake it was, even before Steve said what it was. He never ceases to amaze me in this knowledge!! At any rate, back to our breeding pair, even if they don't breed again I think I'll be able to adjust conditions and choose some more corys (maybe some bronze ones in the future) so that we can have some more breeders.

FWIW, the first time they bred was after a water change with cooler water than in the tank, and I also used a bit of Pimafix since the mommy (never knew then she was a mommy) had some red patches on her skin/scales. Every now and then, usually before she lays, I will see a red patch on her skin. At first I thought it was a sickness, but now I wonder if it was brought on by her body using so much energy preparing the eggs.

Do you have an opinion on whether the planaria would be edible for the little critters...?? If they are food, then I suppose there is no reason to kill them with "No Planaria" or similar "medicine".

[syno321]

First I can't give you any advice on dealing with planaria as I've never had a problem with them. (not bragging, probably just lucky) One safeguard that I always use to prevent overfeeding is using Red Ramshorn snails in the tank that I'm raising the fry in. I introduce the snails as soon as the fry are hatched. The snails can't really compete with the fry for food, and don't pose a threat to them. My go-to first food for most Cory fry (especially albino aeneus) is microworms. I introduce a small amount a day before I think that they'll be free-swimming and then I'm assured that there will be live food available for them when they've used up their yolk sac and want to eat. The microworms live for days in the water, and so rarely die and spoil before they are consumed.

[bekateen]

Hi Moose-Dad,

I like your father-son story. I have my aquaria now because my son wanted one and so I got him started, and then we took off together from there (although my son is a little older (a teenager), and I know I'm more interested in the fish than he is! LOL)

even if they don't breed again I think I'll be able to adjust conditions and choose some more corys (maybe some bronze ones in the future) so that we can have some more breeders

Are you aware that bronze Corys and the common albino Cory are the same spp. (

Corydoras aeneus

) and, from what my friends have experienced, quite happy to cross with each other. The result they got were a bunch of bronze babies, not a mix of albinos and bronzes. So if you want to get more albino babies, you might want to keep any bronzes you buy away from the albinos.

My go-to first food for most Cory fry (especially albino aeneus) is microworms.

Where do you get live microworms? Do you buy the colony starters that are advertised on the internet and then grow your own? Or do you buy live worms from a local supplier or LFS? None of the LFS in my area sell them (to my knowledge).

First I can't give you any advice on dealing with planaria as I've never had a problem with them. (not bragging, probably just lucky).

I haven't had planaria either, and I don't know if they pose any health risk to the fish. What I have had in my tanks, but I don't know how much of a problem they've been, are leeches and hydras. Both are potentially big problems, since many leeches are egg eaters and would probably enjoy small fry if they can catch them, and hydras are also predatory and have the stinging tentacles that can immobilize prey.

I know where the leeches came from - they are contaminants among the live Tubifex I buy from my LFS. So far, I've never witnessed any of my adult fish, not even my cichlids, eat the leeches, so the leeches aren't good for fish food in my tanks. But at the same time, I've never caught the leeches that persist in my tanks biting any fish or eating any fry, and eventually the leeches turn up dead. So I suspect they may subsist on uneaten fish food for a while, but eventually die in my tanks. I have no idea where my hydra came from. I suspect they may have hitched a ride in on some of my plants from LFS. In my tanks filled with adult fish, I never see the hydra, and in my hatchery/fry tank, I've never seen them. But in the 10 gal tank that I use to grow out my fry, there the hydra will occasionally flourish, forming dense colonies on the glass, usually right under the splashing outflow from the HOB power filter; then, as abruptly as they appeared, they disappear again for a few weeks. But it's not because my catfish fry are eating them because this cycle occurs even when there are no fish in the tank.

Cheers, Eric

[syno321]

You should be able to get a microworm starter from someone in your local aquarium club? I've had a culture going for the better part of the last 30 years, unless I've forgotten about them and the culture(s) have died off. Then I can usually get a starter culture from some of the people that I had previously given starter cultures to in our club.

[bekateen]

Okay, thanks.

[Corycory]

Do you have an opinion on whether the planaria would be edible for the little critters...?? If they are food, then I suppose there is no reason to kill them with "No Planaria" or similar "medicine".

Not sure if this was answered or not. First make sure you have planaria and not detritus worms which result from overfeeding. You can check with magnifying glass and see if what you have looks like planaria from the google images. Planaria has a specific head.
Detritus worms are thin, tend to float in the water or stick to the glass and move in an "S" shape. They are the result of overfeeding. They are harmless and fish eat them.

Planaria on another hand is dangerous to small fry. A bigger worm will kill a small fry. They don't pop up from overfeeding but get introduced via plants and such and then obviously multiply and grow in the right conditions. Even large fish don't eat planaria, especially if they've tasted it once.

As for baby deaths, you've figured it. It's always most likely bad water conditions caused or combined with overfeeding.