Hi there, do they have separate tanks ? If not, you need to set up another one ASAP, really tonight. It will happen again. Can you get a better picture ? It doesn't look bad at all, if you can just keep it clean it should heal. Raw honey [ it must say raw or unpasteurized ] is an excellent wound dressing if you have some. The ointmemt you have will be fine as well.
Just be extra careful that there are NO loose bugs in the tank that will get on the wound now. He should be fine.