Ok! I think it works now, third time lucky.
At the moment its in a 3ft tank on its own. It needs an upgrade it been in there since itwas 11cm and is now about 16cm. Its stuck in that tank for now cause its too small gor the big tank and I worried it'll get nailed by my gars.
When I first got this Aro it had symptoms of a swim bladder problem and swam on a slight angle, gulped alot of air, passed bubbles from its anus and had a dropped or bent tail. All these symptoms were consistent with this article.
http://arowanaclub.com/stories.php?story=03/03/02/6700203It now is healthy and has grown out and has none of these symptoms except for a relly noticeable bent tail.