Identification help please

I have been fishing lake Granbury using live perch around the 4-6 in range larger size. I am fishing them under a bobber in 6-8 ft of water. Fishing about 5 ft deep using big bobbers so i know the perch can't pull the under as that are homemade. But what happens is something will come along and slam the bait and bobbers disappears for about 2 seconds the pops back up. Whatever it is will do this over and over until it kills the perch then will not touch it anymore. There are no teeth marks so I can rule out gar. No damages to the bait like no scales missing no fin damage. I just can figure out what is killing the bait then not eating it just killing it. Any one else ever had this happen or any ideas on what could be doing this?

Dinks and they could be any species. You float a medium sized prey fish off the bottom up in shallow water he’s gonna get pecked to death. Chop some up into 1x3 chunks and use a 5/0 or 6/0 circle hook and you’ll know if they are catfish. Or you could downsize your whole baits to a 2-3inch bluegill if it’s scaled fish that are pecking it.

I have experienced something very similar gar fishing

I have tried that different size perch but nothing touches the smaller ones for some reason. I am also running two poles setup with cut shad as well but nothing has taken those baits....I have fished thus spot the last five days in a row with the same happing every time out. And it's strange because they are not just pecking at the bait...the bobber is slammed under instantly for about 2-4 second the they let it go...been fishing ng for cats for over 30 yrs now at all different lakes and never seen anything like this

The bobbers I am user are homemade slip bobbers made out if pool noodles...they are good size and takes some good force to pull the under...

that was my answer too.