Sorry to hear you and the Tang are having to deal with this. As you probably have researched, HLLE is often multifactorial. Stressors such as overcrowding, poor water quality, or poor nutrition may predispose fish to HLLE. The exact etiology of this syndrome is unknown. Proposed causative agents include hexamitid parasites, activated carbon/carbon dust, heavy metals such as copper, stray electrical voltage, ozone, ultraviolet (UV) radiation products, nutrient deficiencies of vitamins A and/or C and minerals, and various other stressors. It can be treated, although it requires good water quality, varied nutrition and use of a topical medication: 0.01% becaplermin (Regranex®, Ortho-McNeil Pharmaceutical Inc., Raritan, NJ). This is an expensive medication and it requires anesthesia to the specimen being treated.
I think we all have been in this vote sometime during our “quest to have a piece of the ocean.”