C. Duplicareus fry problem

cliner · Post by **cliner** » 18 Sep 2007, 22:30

I have a pair of C. Duplicareus that have been spawning since August. Their first spawn ran from April to June. Something strange is happening this time around. After several days of hatching a majority of the fry develop these extended "bubbles" attached to them. They eventually topple over and die.

I don't think it's their yolk sac, it's more like their swim bladders have gone haywire. Feeding only microworms. Two WC's a day.Temp=76F.

Anybody ever experience this and know what's wrong. I never saw this problem with the fry from the previous spawning cycle.

Thanks in advance,

Cliner

bronzefry · Post by **bronzefry** » 19 Sep 2007, 14:50

Have any fry survived? Or do all the fry die at once?
Amanda

apistomaster · Post by **apistomaster** » 19 Sep 2007, 16:23

My C. duplicareous spawned a few times last Spring just before my house temps became too hot through the Summer. All the eggs went bad prior to hatching. They were in my tapwater only which is borderline soft to slightly hard and the pH was too high.

Now that it has cooled I am planning a spawning set up with most RO water peat filtered to a pH of ~6.0. I am thinking it is necessary to match their natural water conditions closer. Corydoras newly hatched fry are very sensitive to pollution so feeding small amount of live food frequently is my plan. The acidic black water also tends to discourage bacterial growth. That is what I think is affecting your fry. Not a specific fish disease but more likely a side effect of pollution. That's my working hypothesis. Other Corys I have bred from similar water as C. duplicareous did better when I matched the natural water conditions.
Shallow water has helped also. Six inches deep. This may just help by keeping them in closer proximity to the small amounts of food used. Or maybe they seek the shallows when in the wild at first? These are just some of my thoughts because I am not sure exactly what the ideal conditions are for these Corys are yet. I will be working on them soon.

cliner · Post by **cliner** » 19 Sep 2007, 17:59

First off, thanks for the replies. About half the fry have survived. The fry are raised in a large specimen container with about 5-6 inches water and an air source. I feed MW twice a day and perform daily WCs. The water I use is a mix of rain water and tap. The PH is 7, KH 4.

The only thing different this time around is that I'm using a MW culure from a breeder that uses a different culturing medium than I use. He uses some kind of mix he purchased from Kens Fish which is red in color.He uses this on all of his variuos cory fry I use instant mashed potatoes.

Maybe I'm getting some of the culturing media into the fry container and that's what causing the fry to bloat. I'll switch cultures and see what happens.

mummymonkey · Post by **mummymonkey** » 20 Sep 2007, 18:21

I've seen something similar with dwarf cichlid fry that was caused by using cool fresh tapwater. As the water warmed up the gas bubbled out; some of it on the tank glass and some within the fry.

apistomaster · Post by **apistomaster** » 20 Sep 2007, 19:43

50% survival rate is not bad. Room for improvement? Sure, but still not bad compared to some Corys from similar conditions wild C. duplicareous are found.

The gas bubbles released from freshwater are probably not harmful. Easy enough to control by normal aging; even if for only 24 hours before using. The conditions necessary to produce true nitrogen supersaturation caused deaths are extremely difficult to induce or reproduce in aquariums at normal tropical fish keeping temperatures and pressures.

cliner · Post by **cliner** » 20 Sep 2007, 20:11

The water I use is a mix of rain water and tap

I guess I should have clarified that my water comes from aged grow out/breeding tanks. Maybe I'll increase the temp a few degrees and see what happens.

And i have to agree with apistomater, 50% survival is not all that bad.

Thanks for the replies.

bronzefry · Post by **bronzefry** » 20 Sep 2007, 21:07

Please also keep in mind that the fry grow quickly and their waste products grow quickly, too. Increasing the amount of water in the tank may help a bit. Just something to keep in mind.

Amanda