Water parameters are- PH 8.0, Ammonia 0, Nitrite 0, Nitrate 5. Water temperature is very high because there's no air conditioning, stays about 84-86 degrees. I probably need to invest in a chiller.
He's the only tank inhabitant in a 20 gallon tank, he's been living in it for 3 years.
I feed him mainly krill, with mussels, squid and/or crab meat. He eats every few days depending on how hungry he acts. 30% weekly water change, tap water with no additives except dechlorinatior/chloramine remover. Last water change was about 5 days ago.
What could be wrong with him? Sorry for the huge pics, I don't know how to edit photos.

