sorry but your tank is too small for them they do need brackish water as they mature and dont do too well in freshwater after a while. They move further towards the estuary in the wild even nearly even becoming fully marine. they also do better in shoals. so 75 gallons is far too small. even for one.. sorry
How about some Giant Danio's or some Hatchet fish, A type of Tigar Barb.A Red Tail Black shark would be lovely too but you can only keep one of them as they will fight. Gixer is correct about the Columbians im afraid. Good luck
well.. seeing as clown loaches and plecs grow to a considerable size, i'm kinda hoping that my top level dwellers will grow to a size where they won't seem so dwarfed by my bottom dwellers.
i'm not too surprised about the tank being too small for the sharks, i was thinking that myself.
hm... i wonder how much my 2 bigger tanks can fetch? haha.. maybe trade those in for a HUGE tank