Big red spots

[JEAE21]

In my turtle tank, the big feeders have been showing these red spots right where they're fins are jointed to the body.
are they fighting each other or getting burnt from the heater?
it looks like blood

since if it's my turtle attacking them, they wouldn't have red spots but would just get swallowed.

 

[Druu]

Quarantine. You shouldn't be keeping feeders in the turtle tank as they add to the bioload.

 

[ShadowBass]

It could be many things, including a bacterial infection. Not sure if those kind of bacterial infections could be passed on to turtles, but I would not be feeding unhealthy feeders to any reptile. From my experience with snakes, reptiles can still catch certain intestinal parasites and diseases from live food.