My Queen has some veins showing in her tail too and I've asked fish experts about it, they said it was because she is such a big fish that you can see the veins in her tail because her tail is so big, not becuase of stress...she's been in my 30 gallon for 2 years and now she is over a foot long, don't worry I plan on getting a 60 to 70 gallon for her this spring, but if a fish would get that stressed over the space they have then I don't think the fish would grow as big as it did, fish know their limit, they grow to the size of their space, and my fish is still growing. That Sarasha comet is still a very small small fish and would do fine with a 30 gallon for now. I"m sorry but I"m just stating my opinion.