Black Ghost Knife Fish Growth

[NeilFishman]

Hi everyone,

Pretty new to the fish keeping community and I recently got a black knife ghost fish. The aquarium shop owner said that I'd eventually need a bigger tank, but wasn't specific. As Im sure everyone in this community knows they need a lot of space as they grow; I'm reading 100 gallons minimum.
At what size should I consider upgrading to a 100 gallon tank? My BKGF is currently ~6" in a 40 gallon tank.
Also in a 40 gallon tank, are there any fish species recommended as a tank mate?
Though I feel I should wait to introduce one, until I get an answer to my original question.
Please advise. Any information is useful, he seems content at the moment with plenty of hiding spots, good water parameters and he's not shy. I managed to tong feed him day 3! But I'd like to provide him with a good environment to live his life when he is fully grown...

Thanks!

 

[Fishman Dave]

Whilst they are very manouverable and can hence probably live in smaller tanks than some other fish. Just to give context. I upgraded mine from a 100 community to a 180 at around 8” as he was looking cramped and out of place. Then from the 180 to the pond at around 14”.