datnoids are slow growers once they hit 5" marker. so a 55-60 gallon will last you a pretty good amount of time. but that depends on how many you are getting.
ph lvl should be at 7-7.5
water temp. between 82-89
more filteration the better.
live plants are optional
you can leave the tank bare or with sand. i prefer sand because its easier to clean left over food.
smaller they are feed them 2 times a day. something small enough to fit their mouth. such as live black worms or blood worms then you can gradually move up to something bigger as in krill. *Note* datnoids love krill its like fish crack too them.
as far as the ngt's go get them in odd numbers. they tend to be aggressive when there is a pair.
tankmates- arowana, clown loaches, cories. other species of datnoids. peaceful cichlids. catfishes, only certain types such as cories synodontis pictus cats. tigs.
you can also add bichirs like the albino senegal, delhezis somewhat peaceful types. iwouldnt recommend Endlicheri, congius, bichir bichirs. with little datnoids.
and do small amount of water change once or twice a week if your not over feeding them. and that should be about it.
alot of steps but its pretty simple stuff to remember after a while. GL with the fish keeping.