Red Eared Slider Turtles Eating Others Alive

Question
Hello! I have 4 red eared sliders, we recently noticed two of the medium sided turtles have large gashes in their necks, we have kept the smallest one on a watch. I regrettably say, the smallest turtle has been eating the other turtles necks and have making them bleed. This particular turtle has been removed from the tank in order to keep all three of the others safe. I'm afraid to now put my one turtle back due to the condition of the others. I wanted to know what to do before moving forward. For the time being, I am keeping the one turtle in a fish bowl with some food and water in a very sunny window. The main problem I have recently realized is that my turtle won't eat his food. He normally eats freeze dried meal worms and river shrimp with food pellets. My sister and I are now afraid he will only eat stuff that will bleed. I'm not sure what to do but I'm scared and desperately need and experts advice. Thanks. HELP

Answer
Hi Emma-Grace,

I'll probably need more information (turtle sizes, tank size, type of lighting/UVB, temperatures) to give you a more accurate reply, but based on the information provided, it's very likely that the behavior is due to overcrowding in the tank.  Overcrowding will often lead to territorial or bullying behavior, which in turn leads to injuries, stress, illness, etc.  You didn't say how big your turtles are or the size of the tank, but even four small (hatchling size, say 2" each) will need a 75 gallon tank.  If your turtles are juveniles in the 4" range, they need 100+ gallons.  You can figure approximately 10 gallons per inch of turtle, although when you're keeping multiple turtles together, more room than that is desirable to reduce territorial behavior.  With multiple turtles, a large outdoor pond is the ideal setup.  So suffice it to say, it's not feeding/cannabalistic behavior, but it is aggression, and you likely need either a much bigger setup, multiple setups, or fewer turtles.

The separated turtle should be removed from the sunny area.  UVB rays won't penetrate window glass, and direct sunlight risks overheating.  He should be in a properly set up tank, with filter and UVB lighting.  Fish bowls aren't appropriate for turtles, and again, housing that is too small will cause stress and possibly illness (poor water quality will also lead to health issues).  

It would also be a good idea to work on improving diet.  Pellets are good, some dried foods are fine, but they should also be offered fresh animal protein and greens on a regular basis, with as much variety as possible.  I'll provide some links to housing and care that will have lists of foods to offer.

If you'd like further help, please post back with additional information so I can give you more specific advice, but the problem you're having is very typically one of overcrowding and will improve with more room + sight breaks, hides, additional basking areas, etc.