i've lost 2 angels in the past couple of months to internal parasites. they would try to eat but kept spitting it out and eventually died of starvation or secondary illnesses. i'm trying to possibly find the source in my fish tank, and the only thing i can think of is driftwood. could it just get in the water also through a water change? my latest victim is a couple month old angel. i had bought two siblings at the same time. the one who is sick is two times smaller than the other. does anyone know what could be happening? although i have other fish in my tank, but none of them are having this problem. could this indicate this parasite is a heximatia (or hole in the head)? thanks!