the only worry you have is that the arrowana will grow much faster than the eel, I have kept both in a tank but my eel was 26" and my arrow 18" til it smashed through the lid trying to chase my cat who sits on the tank..
He may not be eating due to the nitrate level in the tank as even though they are small there is a lot of waste going into the tank as both fish eat high protien diets.
I would increase the water changes to every 2-3 days until you get the next tank. I wont lecture on tank size as you are well aware of the fish you have.
the only advice is i would buy the 300g and not waste the money on the 90.. just my opinion as i have done the same over the years..
They do take a time to settle but my arrow grew roughly 2" a month on a diet of lance fish and canivore pellets. he slowed down a bit at 16"
He may not be eating due to the nitrate level in the tank as even though they are small there is a lot of waste going into the tank as both fish eat high protien diets.
I would increase the water changes to every 2-3 days until you get the next tank. I wont lecture on tank size as you are well aware of the fish you have.
the only advice is i would buy the 300g and not waste the money on the 90.. just my opinion as i have done the same over the years..
They do take a time to settle but my arrow grew roughly 2" a month on a diet of lance fish and canivore pellets. he slowed down a bit at 16"