Fry changing color to black incrementally then dying. Suggestions?

[Holynehpets]

Hello all,

I have 7 breeding pairs and have noticed that when the fry are separated from the parents (at about a month) I get some fry that starts to change colour incrementally. A few weaker fish will darken (know this is a sign of stress) but the way they change color is very distinctive and I was wondering if this is indicative of a particular pathogen or indicative of some recognized malady (i.e heavy metal poisoning etc).

I have attached a photo to show one fish that has half-turned black, is the turning black in stressed fry a slowly progressing thing? I have seen fry that are 'sick' turn dark all over, but not seen just a segment of the body turning black, which eventually will result in the entire fish going black, struggling to swim, and remaining generally close to the surface.

I appreciate there are often numerous possible culprits and many many factors (h20 parameters etc) to consider.

I have been using a hospital tank that is not on my central system and it seems like the hospital tank has become more of a morgue. I separate any fish that start to darken in my baby grow out tanks, but it seems that 2x water changes per day with 0 nh4, 0 no2- and minimal no3- doesn't seem to make any difference.

As mentioned above, is the darkening of 1 portion of the body first (the hind or front) followed by a few days later the darkening moving throughout the body, followed by labored breathing and listlessness indicative of something in particular or general malaise?

I have done a potassium Perm 1ml / 10 L bath and it made no difference on the fish with these symptoms. However maybe the fish are 'too far gone' and the PP was too little / too late, or an internal infection could be the issue, but then it wouldn't explain why the problems seem to spread quite rapidly in the hospital tank.

Regardless, I have some broad-spectrum anti-biotics in the post, so shall do some experimenting to see if a pathogen can be isolated and a cure be found.

Thought and advice are greatly appreciated!

Regards,

Nehpets



129602

[Second Hand Pat]

Hi Nehpets, you might want to read up on the 30 day syndrome. I have fry approaching the 30 day mark and asked a well know breeder (you guys know Cary S.) about preventing it. He suggested keeping the water, tank and filters very clean. So I have been doing large daily water changes, wiping the tank sides and bottom and rinsing the filters weekly.

Regarding the fry pictured that appears to be nerve damage (at least in an adult). Was it perhaps handled roughly when netting or removing the parents?
Pat

[LizStreithorst]

That kind of color change is indicative of an injury like crashing into the tank wall as in whirling disease. I have never seen that in fry so young so I hate to just out and say that's what it is. I wonder what Cliff thinks.

[smsimcik]

It's indicative of nerve damage, as you say, from and injury of some type. I've seen it many times after a large water change with water that is several degrees colder than the tank water. Not sure if that's what happened here or not. Like Liz, I've never seen it in juvies this young.

[coralbandit]

When I researched this I found it to be a possible color controlled nerve was pinched by a thyroid tumor .
This from Handbook of Fish Disease/ Dieter Untergasser .
I have seen this in a few rams over the years but not whole spawns or even any show of it being contagious .
The fish never recover is how I understand and it is so rare I just place the one in the freezer .

[CliffsDiscus]

That kind of color change is indicative of an injury like crashing into the tank wall as in whirling disease. I have never seen that in fry so young so I hate to just out and say that's what it is. I wonder what Cliff thinks.

I think this might be cancer, first starting darkening color from tail then sometimes
the rest of the body. I have seen some adults Discus half black locally and in Asia.
Breeders would call this type tuxedo and
penguin and half moon.

Hopefully this is an isolated problem with
one breeding pair of inherited cancer and
not widespread in the hatchery.

Cliff

[H_ENia]

Hi guys, I also have this problem
I think this happened to me because of the shock of PH, temperature and salt
I dissolved 40 grams of salt in a glass at a temperature of 50 degrees Celsius and pH 8.5 and poured it into the tank and I think it was poured directly on one of the fry and the next day I encountered this phenomenon