Raising Cory Fry

[jameson_uk]

I have had a number of attempts at raising Cory Fry but they always seem to end when the fry reach 1cm. I now have three fry left in my grow out tank after fishing the largest one out today and it was exactly 1cm


I wasn't sure if this was diet and this time I have been trying to feed some Grindal Worm. Not sure how much to feed them though. They only seem interested when I use tweezers to almost place them on their heads. I have been trying to ensure I see all of them eat at least one worm but is this enough? I am also adding Hikari first bites and instant baby brine shrimp.

Is it just a fact that the numbers that make it are low or am I missing something?

 

[dino21]

Hi,

You might have seen my Dwarf Cory thead below where to my surprise we have several young ones appearing in our small community tank.
https://www.ukaps.org/forum/threads/pygmy-cory-new-arrival.61424/

The tank only get standard dried and frozen foods in the usual way, with some small catish pellets, yet they appear to be growing well.

Could it be that you grow out tank is too 'clean', not having any plants or algae growth they might need ?

 

[sparkyweasel]

Could it be that you grow out tank is too 'clean', not having any plants or algae growth they might need ?

That could be it. You could try using leaves (catappa, oak, beech) to get some microfauna going in your grow-out tank. It's good if they can graze between meals.

Do you start feeding the Grindal worms along with their first foods? It might help them to recognise them as food. eg: if you start them on microworms, mix a few Grindal in with the micro when you think the fry are big enough to take them, rather than change from microworms to Grindal.

Can you give us some more details of how you raise them? Also, what species of Cory?

 

[jameson_uk]

They are Sterbai Cory.

It is a 18"X10"X10" tank I setup, added about 2cm fine sand and a Hamburg Matten Filter. There is a covering of frogbit and several alder cones.

Previously I have tried in a 2l HOB type breeder that was plain bottom. I didn't have any live food but the results were the same, I got them to 1cm but no more.

I forgot that I have also been using some liquifry.

I will add some leaves from main tank (there are some catappa and oak leaves in there).

 

[sparkyweasel]

I can't see anything wrong there.
Some people don't like Liquifry, but I do, and I've raised Corys on it.
Have you got any moss in your main tank? That's usually full of tiny life too.
I take it you're doing water changes.
I'm a bit baffled as you've had the same problem in two different set-ups.
Hopefully some-one will have some more ideas.

 

[Polly]

Was the sand brand new or used?
Whenever I've raised Cory fry, I've used the limpopo sand from the main tank, just enough to cover the bottom to about 3- 5 mm, java moss, Limnophyla aquatica weighted at the bottom and Salvinia natans - all taken from the main tank where the parents live. The water comes from the main tank too. There's a light over the tank/Jar (yes I've raised them in a 3 litre glass jar too. No heater, the temperature is about 20C. pH below 7

The filter is a mature piece of sponge kept in the main aquarium filter compartment so it's always ready to go. It's slipped into an uplift tube and an airstone does the rest, just enough air power to move water through the sponge slowly.

All this means that there's more than enough friendly bacteria to cope with the needs of baby fish. Small daily water changes also help - 10 to 15% ensures no huge swings of parameters. At first, waterchanges use water from the main tank, once they start needing to be fed regularly, I start making fresh tap water changes.

Feeding, I don't feed them at first, they just graze on the plants, moss, and gravel eating whatever is available, after they start looking like a baby fish, I use the 'dust' from the food the parents get, good quality flake is useful at this stage (last time, I used Fluval Vegetable flake) I grind it down until its dust and only a very tiny amount, whatever sticks to a dry finger tip about 3 times a day - I have tiny fingers 😉 The rest of the time they pick at what's in the plants and in the sand. Most people give fry far too much food so it's best to be cautious, that way the water doesn't deteriorate so quickly.

The reason for the plants, apart from providing micro-organisms to graze and using up any ammonia produced by uneaten food, is that the fry need to fill their swim bladders at the right time and also need to access air for their labyrinth organ regularly . Being so tiny it can be difficult for them to get to the water surface. The plants allow them to stay nearer the surface and also protect them from any excess water movement from the airstone. At first, they spend most of their time in the plants.

Once the baby fish are about 1/2 an inch long, I put them in the main tank where they do really well. By that size, they are too big for my other fish to try eating as they have small mouths. I've done this with A. borellii in the tank, but wouldn't with fish like A. agassizii.

I hope some of this helps. It's difficult to advise not knowing all the parameters that you have there.

 

[jameson_uk]

So I managed to raise two so they are now approaching approaching 2cm.

I am fairly sure these two are from the initial batch I transferred from the hang on breeder box I did add about 14 eggs from another batch but it seems none of these survived.

The Cory's in the main tank spawned again today so I will transfer the eggs later but I am wondering whether at this size the fry I have might eat the next batch (I wonder if the last batch was done for by the existing fry and some bladder snails which seem to have made there way in).

I am guessing they are fine to go back to the main tank (their tankmates will be otos, other corys (fully grown), black neon tetras and amanos. It is only the amanos that concern me as they seem to have an evil ruthless streak.....