I recently noticed one of my harlequin rasboras to be really skinny and small when compared to the others. After observing more closely, I realized that the fish is not eating at all. It is obviously weak, getting sucked into the current of the filter at times. I moved it to a smaller tank, but so far no success. It is not bullied or bothered at all in my bigger tank. Any ideas as to what could be wrong?
