Experience with a mandarin fish?

try switching him over to some frozen. have had good luck with blood worms and keeping sponge in there helps too.

 

Also try cyclop-eeze. I have heard good luck of people training mandarins to eat this

 

He may eat brine and mysis shrimp. It seems very strange that you have had him that long and suddenly he seems skinny. When is the last time that you saw him eat? Can you provide more information? Have you added a new fish? Have any other fishes behavior changed recently? Are your water parameters the same?
He may be getting sick...possibly something internal? More info might help if you can provide any?

 

This is not the first time I have heard of this. It may be something as simple as an odd param that is throwing him off or a serious illness. If you can I would try to get him in a tank by himself until he fattens up a bit, My mandiren was starting to thin down but before I could catch him he took a ride into the sump and is fat and happy down there. Shaun

 

He might have eaten alot of your pod population.

They are VERY hard to train to eat frozen food (MOFIB.ORG has good ino on this).

If you have a refugium or sump I would put him in there for a bit & let him eat on those pods while those in your main tank have a chance to recover.

GL
Craig

 

+1 on the blood worms. Mine took to them right off. You don't mention how big your tank is, or if you have a refugium. It also helps to feed your tank phytoplankton. I have a 75g with a 55g tank for a sump/fuge and I don't have to add any pods. Just dose a little phyto every few days and there are always pods running around.

 

There is a guide on nano-reef to training a mandarin onto frozen or even pellets. If you are going to do this I'd recommend getting a good skimmer though because it seems like you'll have to be putting in a good amount of food.

 

we have had great luck with ours eating the cyclop-eezz - he got fat fast!