1.Clean, cycled with no ammonia or other stuff water. Less than stellar conditions stress them and can lead to nipping 2.IAL, tannins seem to calm my boy down and act as a destresser 3. Panty hose test everything before it’s put it 4. Box filter so the idiot doesn’t intake tube rub 5. Frozen diet Even with all that they can nip or get fin rot. It can grow back but it can be a long process depending on damage.