Super aggressive angelfish?

[IHaveAquariums]

My 36g tank had 20~ danios and 2 angels with 2 algae eaters, took danios and algae eaters out, left just the angels for probably 7~ days, added 4 corys. Few days later the angels kill one and damage another, I took them out. I've had them for about 4 months now and they got bigger and they have different body shapes and features so I'm guessing m/f. They're also locking lips now and sorta chasing each other. Could they be mating which would lead to the aggression? Also could they be put back with other fish or is it best to just leave them species only now. Thanks!

 

[V227]

Your Danios should be fast enough to survive the Angels. I've never experienced Angels killing Cory Cats but stranger things have happened. Might consider adding a rock or two, or maybe driftwood to provide hiding spots for your Cories.
There was a very recent thread concerning sexing Angels. The general consensus was that Angels are very difficult to differentiate regarding sex. Males are likely to be bigger, develop a slight forehead hump and have a dorsal fin that is positioned close to a 90 degree angle.

 

[kashif314]

Really there is no proper way to sex angels unless they paired up. If they locking lips means its territorial behavior. Its not angels mating ritual as some claim on YouTube. You can keep them together and see if they paired up otherwise put them in tank with other fish otherwise if both are males they will just fight if there is no dither fish and as v227 said that provide some driftwood and rocks plants if you already didn't have.