Can anyone tell me what I'm doing wrong?

Hello!

I've posted a few times about my sick/injured newts.. I'm down to one Newt now, he lives in a tank with lots of water and rocks and things to climb out on. The water temperature stays above 15 c (70 F) but never goes above 18 c. I finally got him to eat, and he'd take all the food I would give him, mostly just frozen blood worms. I've got a small bubble filter in the tank that doesn't make a current... Recently he hurt his leg and it looked like it was getting infected and it is swollen, so I cleaned the tank and put a bit of tetracycline in the water (he's had some a month or so ago and it cleared up every sign of infection then..) This morning when I checked on him, he's got a cut on the top of his head it's a fair sized hole and it looks like it's bleeding.. as much as I feed him he doesn't seem to gain weight... Since he's hurt his leg he's mostly been spending time on a rock above the water.. he doesn't seem to want to eat much now either.. am I doing something wrong? how does he keep hurting himself? there is a snail, Vlad, in the tank (I've been told to move Vlad, but he's just little and Newt never goes anywhere near him and I don't want him in the other tank..)

If anyone's got suggestions, I'll appreciate any help I can get! thanks!

Are the rocks excessively sharp or jagged? Could it be hurting itself trying to get to food under rocks? What kind of newt is it?

Newt is a little Red Bellied Newt.. or Fire Bellied I guess, I've looked at the species articles on this site but haven't really found a picture that is exactly him.. He's black with a red belly with black spots on it, not blotches almost perfect spots. He's small, no more than 2 inches. The rocks in his tank are slate, they're fairly big, but not sharp... I try to make sure the food doesn't go under them, but he does like to hide behind them kinda of wedged between the rocks and the tank wall... :s

All the slate i've ever seen has some pretty sharp edges. Granted, i've not seen every kind of slate there is, but i have worked with it before and it has a tendency to flake and those flakes can certainly cut human skin. Tumbled river stones are probably much better.

that definitely makes sense John, I'll have a look and see what I can find. I haven't noticed my slate chipping or anything, I got it from an aquarium warehouse so it's supposed to be good.. I will have a look for rounder rocks though! thanks