Every fish is different. In my exprience they grow quickly up to 6-8 inches and then slow down quite a bit. If all you have in there is the pleco and some danios I would say you are fine. Danios have a small bioload.
But would the anglefish be compatible with the danios? Ive seen some pretty nasty attacks down at my LFS with angel's slaughtering perfectly healthy neon tetra's.