I was thinking of stocking my new 20 high tank with an angelfish. Would my neon tetras be ok with an angelfish? I have heard angelfishes will eat neons... What's the smallest angelfish species out there that would be ok? Thanks!
All the angelfish you see are similar species, Pterophyllum scalare which grow to 5-6 inches in body diameter at most. They will eat neon tetras once they see the neons fit their mouths. I wouldn't suggest mixing both species and even try the angelfish in a 20 high. A larger tank is much better IMO.
There are two other species that exist, Pterophyllum altum and Pterophyllum leopoldi. Both are rather uncommon and more expensive and will still eat the neons. The former besides will require a large tank anyway with their extraordinarily tall fins.
there are three species of angelfish some if not all may be available
Altum the largest body size may get as large as 6-7" sans fins
Scalare 4-6" sans fins
Leopoldi 3-4" sans fins
the leopoldi is the smallest of the angels but all may be aggressive to neons.
about the only angel I would not put in a 20H is the altum. it may hit 10-11" tall with fins