Ok just a little bit of back ground. My BGK has recently moved from a 55g to a 180g December just gone. The 180g was a new set-up but the filters used on the tank had already been cycled, and all water tests to date since moving my fish in have been AMM 0, Nitrite 0, Nitrate < 10. WC between 30 - 40% weekly. A couple of days ago my BGK stopped eating he usually is a big pig and is the first one out to feed when I go to the tank. His routine is that he comes to the surface to be hand fed his beef heart or shrimp etc and then see what he can scavenge from the bottom of the tank. Now he comes to the top of the tank takes to food from my hand then spits it out and returns to his favourite resting place. This started about 4 days ago.
I introduced some new fish to the tank yesterday but I don't think this has anything to do with it as he had stopped eating before-hand. Also FYI the fish I introduced had been in a separate tank for the last 2 months in quarantine before introducing them to the tank.
Hope someone has some ideas on what could be going on, as I have had this boy for about 7 years and don't want to lose him.
Thanks in advance