New dat... problems already :( could do with some advice...

Hi, I just got my first tigerfish today, awesome little guy, about 3 inches long. Was sold as a siamese tiger, im assuming microlepsis. Anyway this is my first post in this part of the forum so hello to everyone Ok, so heres the problem... Like I said new tiger, about 3 inch long, seems quite happy although very skinny with concave belly. Im not worried about this cus most fish are skinny when you get them... Hes minding his business swimming around exploring his new home... But he seems to have made an enemy already... My firemouth (same size as the tiger, but nice and fat) HATES him, and everytime he sees him chases him frantically till the tiger gets out of eyeline... Now i know cichlids can be nasty little pieces of work, but firemouths generally arent too bad, and the one i have is very placid normally. There doesnt seem to be any actual violence going on, at least not yet... just chasing but im sure it isnt very nice for the tiger... Should I be worried? Assuming he isnt being physically harmed, is being chased going to bother him to the point of harm? Ive never had a tiger b4 and although Im sure there would be little issue if he was bigger and well fed, is he able to take being hounded around the tank? Dont get me wrong, it isnt constant, the firemouth isnt constantly hunting him down, its only if he actually sees him, chases for a bit, loses him and thats that. at least till next time he sees him! Push comes to shove the firemouth will have to go, but im hoping it will settle down, i mean, its only been 3 hours since the tiger arrived. Any ideas anyone? All help much appreciated. Oh, tank is 48x22x16, I know it isnt big enough, but it is only going to be for about 6 months when i will be getting a 72x24x24. tankmates are filament barbs, bichir, leopard bushfish, flying fox, bristlenose, hoplo.

Thanks in advance

Indonesian? Ill give it a go with the waterchange and re arrange. cant really add many more plants though. Is his colouring normal for only just 'moving in'? Could someone tell me what a stable or unstable dat is? Is it visible stripes as opposed to all one colour? Also, and im not disputing what you are saying, what has size to do with the species? Thanks guys

Cool, that explains a lot, thankyou. Sucks that ST are extinct, didnt realise that. Gonna rehome the firemouth- all of a sudden he has started beating on my bushfish aswell- guess the tiger sent him over the edge lol. There are plenty of hiding places in there for him, roots/ caves, tunnnels etc, so like you say hopefully he will settle in soon enough. Considering he arrived by courrier this morning he seems to be doing fine. He has eaten some bloodworm, not a massive amount, but shows me he is willing. There are a few bits of fish and a couple krill waiting to be eaten too, but he hasnt found them yet. Not sure if he will entertain pelets, Ill find out later when i feed b4 bed. He looks almost white, is that also part of settling in or is that cus he is young? Thanks for baring with me evryone