Black moor hanging at the bottom and corner bound

[Smolson83]

So I have a tank with a regular goldfish, a black moor, and a frog. Did a full tank change almost a week ago, everything's been peachy. The frog nips at the moor every once in a while, otherwise getting along. Then today, the moor hasn't been meeting me with the others at the front when I feed them. Or swimming to the top to get the food. Just sucking on rocks and looking like he's not feeling well....
Was only in the one corner, recently swam to the other corner

 

[fishot]

Welcome to the forum!

The frog's nipping may be what's causing the moor to hide.