u could go with a if u want only one fish these are some good ssize fish that would do good in yo tank only a short list. u could also get like 10 or the black arowana and some might form a pair then u reteurn the rest of them lol.
GATF
VATF
jadini arowana
silver arowana
black arowana
RTC
TSN
Wels catfish
florida gar
spotted gar
tropical gar
cuban gar
long noes gar
short noes gar
Lerius pictus
zangro
P. ansorgi
P. bichir bichir
clown knife
royal knife
dovii cichlid
FH cichlid
leo ray
P 14 ray
moto ray
marbel moto ray
amaratus
pima
cichla
fire eel
tire track eel
paroon shark
ID shark
Tigrinus
graffie catfish
pacu
midas cichlid
red terror
black shark
cigar shark
megaladoras
giant gourami
Mbu Puffer
snake head
aba aba knife.
channa micropeltes, monster of all fish the freshwater equivelent of a great white shark. keep one of these beasts great looking and they dispatch anything placed in there domain so beautifully. theyre real mean when they have there own aquariam for a long time, they find other fish intruding rude, like an insult!