I would go ahead and start an Epsom salt (
Not aquarium salt) and tannin treatment.
Good that you lowered the water level, however, it might be easier to treat him in a small QT that you can float in the heated tank to maintain water temp of 76-77F for treatment. Cover the QT with plastic veggie wrap to help retain heat/humidity for the labyrinth organ. Light off for the first 24h-kept in a dim lit quiet location.
Premix some treatment water in a 1gal jug of dechlorinated water. Add Epsom salt 3tsp/gal and a tannin source if you have one. Either IAL (
1lrg crushed/gal) or naturally dried and fallen from the tree Oak leaf (2
0 crushed/gal) Let this steep for 30 min...shake well before use...
Using this premixed treatment water-Make 25% water changes every 15min for 1 hour today.
He needs to stay in the covered QT in the treatment water for the duration of the treatment period of 14 days.
Tomorrow-using the premixed treatment water make 50% daily water changes for the next 13 days.
If you used a tannin source- the premixed jug of water should look darker each day and this is what you want.
Nutrition-good quality varied diet fed in small frequent meals. If you have access to live mosquito larva offer several rinsed a couple of times a day.
Good luck and keep us posted....