Your BTA's are lovely. I've never had one get as large as your RBTA. Do you know the region of origin of that RBTA? It's so beautiful. Your tan BTA is also very nice...so healthy and crisp.
The pictures you posted suggest your tan nem was lacking some zooxanthellae at one point but was still biologically functioning, at least to some degree, well enough. Then, likely due to your good husbandry practices, it gained zooxanthellae and grew stronger. The OP's anemone however, hides from the light and it's tentacles are totally receded. It does not accept food. IMO, it's biological functions are becoming lost. I've been through similar scenarios myself and found it beyond frustrating- so much so that I finally resorted to taking dying nems to a State University that teaches Pre-Vet to have them posted. It was not a marine-based program so the most they could offer was tissue cultures but they seemed as interested as me to figure stuff out. Over the course of several months I had the tissues of several failing anemones cultured at different stages of demise and 100% of the time anaerobic bacteria grew. I then started testing seemingly healthy anemone tissue with consistent negative results. To me, that suggested a few things. The first being either the environment I was keeping my anemones in did not contain enough oxygen or I was not adequately delivering the oxygen to my anemones, (flow). Second, sick anemones- like it or not- must be prompted to inflate and exchange spent water for new oxygen-rich water. And finally, as someone who routinely participates in the diagnoses and treatment of human bacterial infections, I understood the value of prevention, early detection and medicinal intervention with which I've had some success (w/ people and w/nems
). I also installed UV, which created a separate issue for my sponges but that's another thread.
Clearly, my anemone failures were not the result of ineffective lighting as suggested by most of the Anemone Keepers I consulted. IMO, that assumption is overused and during the course of brainstorming interventions IRL with others having nem issues, IME, it's almost never a lighting issue- especially with BTAs. And notably, when lighting is the issue, IME more often than not the lighting is excessive. The OP is an experienced reefer. Respectfully, it's unlikely his anemone is failing due to poor nutrition or lighting. Except for the new hobbyist who naively places their nem beneath a standard incandescent in an inert unstable environment, IME it's rarely that simple.
