They are prone to internal parasitic infections...
Some lines have mild deformities including a beak like nose/snout, large or misshapen eyes (rare) or misshapen fins... It is highly suspected by many this is due to heavy inbreeding...
I use UV lights to reduce/remove the risk of parasitic infection
others have reported good results at using a garlic supplement when feeding and treating with Jungle Parasite Clear when signs of parasites are noticed.
The most common sign of internal parasites is white stringy poop
I would avoid adding random chemicals in their tank as a precaution. Clear water, a healthy diet and daily observation is the best approach
then treat when necessary with the proper treatment