I don't think there's any ray you can keep in a tank that size..
same goes for gars..They grow fast as well..
Bichirs are good in a 120..I like Delhezi..
for knifefish Clowns get too big and aggressive..a black ghost will work well with Bichirs..
for other oddballs you'll be able to keep a Small Datnoid for sometime..They grow slow..but eventually outgrow your tank..or a Bay snook ,but I'm not sure about the growth rate of these..
you'll need one or 2 upper/middle dwellers to make the tank look full..Nothing comes to my mind other than cichlids..
same goes for gars..They grow fast as well..
Bichirs are good in a 120..I like Delhezi..
for knifefish Clowns get too big and aggressive..a black ghost will work well with Bichirs..
for other oddballs you'll be able to keep a Small Datnoid for sometime..They grow slow..but eventually outgrow your tank..or a Bay snook ,but I'm not sure about the growth rate of these..
you'll need one or 2 upper/middle dwellers to make the tank look full..Nothing comes to my mind other than cichlids..