I've never seen a zebra fry that color. What else are you feeding him? I feed quite a bit of astaxanthin rich food and my fish still aren't yellow. If he's just getting brine shrimp, you definitely need to add daphnia or something instead. Brine shrimp has almost no nutritional value. He definitely does look too thin, also. How warm are you keeping him? That can affect his weight also.
There are a good number of threads on the board on the subject of feeding. I feed daphnia, New Life Spectrum grow food, mysis shrimp, cyclopeeze, hikari sinking wafers, dainichi ultima, and even flake.
Yeah, that temperature will work fine for young guys. I tend to keep mine closer to 86, but I'm a wee bit outside the scale for what most people do. I enjoy water changes and feeding, so the higher temps aren't a problem for me, but I know it could BE a problem without careful watching .
i have my tank at 84-85f and i feed mine hikari sinking carnivore wafers, new life spectrum h20 and growth, osi shrimp and algae/vegetable wafers and hikari algae wafers.
The yellowing of your zebra looks like fish Jaundice more than likely brought about by a diet lacking in vitamin E but it could also be down to liver failure.
I have only seen this once in all of my years as a fish keeper. I suggest that you feed the fish a good dry food containing vitamin E, most do.
Good luck with the zebra, I hope it pulls through.
I'm afraid that meds will have no effect in this instance. Altering the zebras diet is the only real option that could possibly help. That said if the affected zebra is suffering from liver failure there will not be much you will be able to do. I suspect that only the one fish is affected as it was probably predisposed to suffering from this condition. I still strongly advise altering their diet, whilst the others show no symptoms at present it's best to take no chances.
I have also read that improving water quality can alleviate symptoms for fish that are not too far gone but it also has to coupled with an improved diet. Some catfish farms in the far east have been plagued by a similar problem, in that instance it was found to be diet related coupled with poor water quality.