Take it he has a convict community in there? He should def get a thermometer, and yeah like you said maybe keep the temp a little lower, thats if its safe to do so! But too be honest its nearly imposible to keep cons from spawning. Unless you seperate the pairs, maybe he should think about using a divider if getting another tank isn't poss. With the existing fry if their left in the tank soon after they become free swimmers thier likely to be eaten, its difficult to pass convict fry on to any one so I dont really know what to suggest

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I'm sure if ur patient u'll get some better advice from others here, good luck x