nice little guy, mine grew fairly quick. I have both species they are fun fish, his tail looks a bit short. watch for fungus, as one my urua f. came in with a short tail like that and it continued to deteriorate and had to treat to get it fixed... or that tiger barb could be chewing on him.
Should have a fuller tail. Hopefully it is growing back from an injury or something. I do not have a pic of mine when smaller but you can take a look at the tails on my bigger ones and see.
What size tank is it in? I strongly recommend a large tank, especially for multiples.
My last group of U. sp. 'orange' were to 8" in a year but they tend to stay a bit smaller than standard amphiacanthoides. My pandas went from 2" to 8" in a matter of months. Both species appreciate warm water with very low nitrates like discus. I try to keep the nitrates around or below 10, which is tricky if the tank is crowded or not large enough. Uaru are big eaters. I fed mine algae wafers, Romaine, sometimes zucchini, shelled peas, etc. They also got pellets (both veggie pellets and NLS/Hikari pellets), frozen bloodworms, and the occasional mysis shrimp.