is my blue tang doing poorly?

[FreshCore]

I've recently introduced a blue tang to my 250L tank, joining our existing residents - 2 clownfish, 2 cleaner shrimps, a sifting star, hermit crabs, and a coflake. After six days, I tested the tank parameters and everything seems fine. Initially, the tang was quite shy, but after 48 hours, it started feeding well. Prior to its addition, I was feeding the clownfish once a day with tetra marine flakes. However, I've since switched to twice-daily feedings with mysis to accommodate the tang. Both the clownfish and the tang seemed to be feeding well.

But today, the tang has become really quiet and hardly feeds, even with the veggie sheets I got for it - it just won't touch them. It's taken to hiding in its favourite rock, hardly moving. I haven't given any mysis for a few days, but I'm worried about overfeeding. I'm not sure what's wrong. Also, my largest clown looks really fat just behind the Sprig, which I hadn't noticed before.

I've rechecked all my parameters - SpG 1.024, ammonia, nitrate, and nitrite are all 0, pH is 8.4, and alkalinity is 2 (I've added some coflake buff).

[storm9]

I think the issue might be with the mysis, and that you didn't introduce algae sheets from the start. As you know, tangs are herbivorous, so while they can have some meaty foods occasionally, their main diet should be algae-based.

[FreshCore]

I'm really worried now, is there anything I can do to get him eating again, now that he's gone off his food completely?

[felinxo]

Hi FreshCore,

Firstly I think it's unlikely you've overfed your tang, and I also think it's unlikely it's due to a lack of seaweed or algae for a few days. If your tank was being overfed, you'd likely see a spike in phosphates.

I do think he might be developing ich though, tangs are prone to it when stressed. So try to reduce stress as much as possible.

Can you show us a photo of the tang and the clown? That would be really helpful.

Also, I do need to point out that the tang is going to get too big for your tank.

We're all a bit nosey on here, and we'd love to know a bit about you and your tank.

[nixora]

A Blue Tang, more than likely a Regal, is way out of its depth in a 250L tank. I'm not surprised it's stressed, Seffie's right, and I'd be shocked if it didn't have whitespot. These fish need space, at least 5-6ft of tank to be happy. A 250L is just too small, not just for a Regal Tang, but for any Tang. You'd be better off with smaller fish like Blennies, Gobies, or Firefish, they'd thrive in a 250L. There are plenty more that'd be happy in a tank that size, I'm sure someone can add to the list. Best thing to do is take him back to the LFS or sell him to someone with a bigger tank, it's the best for the fish.