Hello, I can tell something about Sphaerychtis… I had 4 of S. osphromentoides in 625 L aquarium with my Satanoperca. They occupy higher part of aquarium (dim. 160x65x60) and they swimming among plenty of ‘Monstera’ roots ( I use plants above aquarium for lowering nitrogen concentration).Satanoperca ignore them , so they have full space for themselfs…. and… they become extremly agressive. Few week after I moved them to this aquarium one of them was killed by another. Few months later I saw spawn and even female swimming with her mouth full of eggs – but even in that large aqua male still chasing her and one day she jumped and die… ( I’m still angry for myself that I did’t seperate her – but I thought that in such large aquarium she will be fine…) And one more thing… Sphaerychtis is most inteligent fish I know – when Satanoperca spawned – they find every occasion to eat the young – even if I seperate brood using plexi plate – gouramis find they way..:):)
Parosphromenus in my observation are more delicate and not that agressive. But if we give them peace and quiet they show us their beauty