I went through that with a Red Sea Regal Angel from Diver's Den. Despite never taking a bite it lasted 7 weeks. I decided to try force feeding but it took over 2 weeks to get everything I needed: syringes, small enough catheter tubing, liquid high energy food, anesthetics for fish, a couple of goldfish for practice,...
In the end it was all for nothing and the fish passed away. Quite likely my lack of fish intubation skills accelerated its demise. I might have better just given it an overdose of the anesthetics to end its suffering.
But as long as your fish is still looking for food or reacting to feedings not all hope is lost.
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