Black spot on my walking catfish???

[clarissasjh]

Hi! I own a marble clarias, the pinkish beige + black/brown patches colour variation of the common walking catfish. I've had it for about a month now, it's around 9cm in length.

My tank is still cycling but the ammonia is currently 0, nitrite around 2-4ppm and I'm doing daily water changes of around 40% to control the nitrite levels. Also dosing prime at 2-3times the stated amount for my current 3ft tank during every wc.

Now for the main point, I recently noticed a new black spot on my catfish's head. It seemed to have appeared overnight or over 2 days the most. Tried to look at it really closely but the catfish was just super active swimming all over the place(if not hiding) and the best I could make out of the "black spot" was that it looks very similar to the catfish's dark pigmentation patches around the body. No bumps, no indentations no weird texture that I could see. The catfish is acting fine too, eating well & active as usual.

I just wanna know whether it's possible for this color variation of the walking catfish to 'grow' new pigmented spots/patches as time passes or is the black spot something I should be worried about?

Attached a google image search of the type of catfish I own and a before & after pic of the black spot appearing




Before the black spot appeared^


Now with the black spot^

 

[thebiggerthebetter]

They are piebald fish. This means the coloration is never stable and can swing from all black to all white and anything and everything in between.

Similar to koi, whose colors are not stable, and other animals.

2-4 ppm nitrite would be deadly was it not for your WCs and overdose of prime that detoxifies nitrite at very high dosages of prime - it says on the bottle what dosage of prime detoxifies what level of nitrite.

Alternatively, humble table salt does the same thing - add 10x-100x excess of salt versus nitrite level, in your case at least 20-40 ppm salt, I'd go with 100-200 ppm, and you are more or less good short term until your tank cycles..

 

[clarissasjh]

Thanks! At least now I'm relieved to know it's not some sudden infection or something..

Anyway, I remember reading somewhere while researching on my fishes that catfish don't do too well with salt, especially when it's not specifically used to treat any illness the fishes are having. Will adding that amount in excess cause any effects on my catfish?

 

[thebiggerthebetter]

IMO and IME this info, which I come across too, is bogus. Catfish in general do as well or as poorly with salt as any general freshwater fish.

Walking catfish is an apocalyptic catfish, exceedingly hardy of all catfish too, by the way.

Anyhow, there is a stickie thread in the Freshwater diseases forum here about salt that pertains to catfish just as well as any other IMHO. I'd gradually add the salt over a day and then gradually remove it over a day or longer.

Many wild fw fish visit brackish waters and even marine environments where the salinity level changes are about as abrupt too. If there is more food there at the moment or the breeding instinct makes them, they do it no problem.