What kind is my lonely datnoid?

[Midwater]

would a smaller Silver be okay long-term in a 55-gallon

No.

 

[SilverArowanaBoi]

No.

Figured...

 

[thebiggerthebetter]

Ours maxed out at around 13". Dats seem to be shy fish apart from the situation when a tank mate might fit in their mouth. The problem with silver dat is that most usually people (us included) lose them after some years in fresh water. They need to transition to brackish, they are the only ones like that, that I know of among the dats. You can read it all in this thread earlier for more details.

 

[Midwater]

Ours maxed out at around 13". Dats seem to be shy fish apart from the situation when a tank mate might fit in their mouth.

Yes.

The problem with silver dat is that most usually people (us included) lose them after some years in fresh water. They need to transition to brackish, they are the only ones like that, that I know of among the dats. You can read it all in this thread earlier for more details.

No. (Much as though I respect your knowledge.)

AT come from the Mae Klong river well before the mouth and the Mae Kwae river (incorrectly called the River Kwai after the film). This fish is definitely freshwater only.