What's are you feeding him please don't say sea food as that's the biggest killer of small tigs below 12 inch feed hikari sinking carnivore
I would get rid of the pipe one you never see the tig two what happens when heal nice and happy in that pipe and you need to remove it because he's to big for it
I would also get rid of some of the other cats you have they are all baby's now but wont be for long and the tig is the softest of them all and will probably get the crap beat out of it
I think your tank is a good size for the tig for a long time but not the other cats
Let's be fair none of them other cats come close to a 12 inch + tig
Right the colour and stripes they change a lot as they grow it could also be stress from the other cats
I saw a aro or 2 in the tank so you have plenty of fish that will be filling the tank up fast without the other cats
I saw a big shoal of massive clown loach with a big tig ones and it looked great
Stop feeding sea foods get rid of the pipes and othercats then wait 6 months and you will have a great looking fish