Bowie, my biggest guppy fry/young adult had his tail eaten. Not just had the fin shredded but the whole thing eaten, and some flesh too. He accidentally got taken from the fry tank and put into the baby loach tank this morning 
He is back in the fry tank, with melafix and salt in the water, he sat under a statue for a while and i was quite sure he was going to die from stress.
Surprisingly he perked up and is swimming around with his friends, eating and still pushing other fish around. He can swim alright, though maybe a bit slower than normal, but he looks awful.
Is there anything anyone would suggest to improve healing and try to lower the chance of infection?