Was thinking about getting a blue acara..does anyone have any experience with them, like tankmates, aggression level. Have heard they are pretty mellow but different answers in regards to size.
Quite mellow compared to larger centrals but they're still quite predatory and aggressive. Will do well with most of your small centrals such as Thorichthys sp., Cryptoheros sp., Archocentrus sp., etc.
Ditto on japes, anything to small to fit in their mouth is a danger, also things like corys could be at risk if you have a pair, single acara tend to leave them alone IME, guess being substrate spawners they see them as to big a risk and byebye cory. As a general rule they can eaily hold their own against anything their size but unless breeding are not overly aggro.
I have had two that were completely non-aggressive and could be kept with anything. routinely got bullied by an angel fish
had two that were very aggressive (for its size). one held its own with a dempsey. another nearly killed a severum and did kill 2 cory cats for no reason (tank was really understocked).
Exactly what Japes says. I have a 4 incher and got it with a firemouth and rainbow cichlid, and soon to be sajica. No issues at all, mine is actually very mellow. If you need any specific questions answered let me know.