Fishes fins are vanishing!!

[rust9000]

Hi,
When i first got my 120g, i had black sand in it, after a month or so my bottom dwellers started rotting from the inside out, so there was a hole in them and u can see their bones, well obviously they died RIP, and after changeing my substrate to white sand all has been fine until yesterday when i noticed my perrunos dorsal fin had started to vanish, it is not looking good, this time i took pictures, so please help me, im ment to be getting a stingray in 4days and i dont want to have to cancel the order unless i have to. Thanks

 

[aquatic-merchant]

if you have other fish they might be attackin the catfish fins.otherwise sounds like a contaminated tank.did you rinse the sand well?you should scrub the entire tank including the glass or acrylic ,heater,filters,tubing,etc...make sure you keep some good bacteria though.if that doesn't solve the problem,maybe your cat has fungus(finrot)use melafix and tetracycline.good luck!!!

 

[rust9000]

No it is not finrot, or fungus as i have seen and treated them in the past, oddball suggest ammonia burn, cant check my water as im not at home (i live in the UK and am on vacation in the USA) and my mum does not know how to use the kit either, but im home in 3days so ill check it then.