Skinny Fish?

[Whitey]

One of my cichlids iv noticed is looking rather skinny, his belly goes in a bit, im sure it never used to be like this. He eats fine, nothing out of the ordinary. Not as active as he used to be tho.

Could anyone tell me what this could be?

 

[Bloo]

Could be internal parasites - not always visible.

I suggest having a look at this thread of mine