Red Tail black shark not eating.

Question
In my 20 gallon tank i have a red tail black shark which is currently around 1-1.5". He looks healthy (jet black with red tail), except he has recently stopped eating and i don't know why. He's also stopped being as active as he used to be (he now just lies down or does a random swim across the tank). Hes not being bullied by the other fish either because he 'IS' the boss of the tank. Any ideas for what is causing this problem and how i can fix it?

PS: hes been in the tank for about 3-4 weeks.  

Answer
Hello,

I would give him about another day and maybe try offering him a different kind of food. If he still won't eat you should treat him for an internal infection, because that is the most likely problem. I recommend Maracyn-2 if you can find it, if not tetracycline.

I hope this helps.

Regards,
Stephanie