Looks real nasty. Probably won't grow back. Half it's body is white. Looks like a fungus infection. Keep your water CLEAN, turn up the temp, and with that injury, I'd go with some Pimafix and Melafix.
naw im pretty sure he will live. just put him in a separate tank to heal him. i wouldnt keep him together looks like the lungfish tried eating half the body and u can see the red marks when he tried to eat the bichir.
From the looks of it there is a huge possibility he will make it. I had one of my fish worse then that make it. In your case just seperate one of them and do some w/c and add some melafix....GL
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