sick fish?

[tarioronar]

I have a 5 gallon tank with 2 tiger barbs, an angel fish, and a alge eater (plcostmus or something, i cant spell the name) a couple days ago, I noticed that one of my tiger barb's color is really pale compared to the other, and it's taken to swimming vertical in the corner on the tank. like with it's nose straight down. It'll swim other places sometimes, but for the most part it stays in that one corner. Should i be worried?

[Shaz]

Hiya!! Being a newbie myself I dont think i can be of much help but I am pretty sure that tank is way too small for those fish (Someone correct me if im wrong) This is a great site so someone will help but like i say i think it might have something to do with tank size.

[Ems]

I'm not too familiar with Barbs, but Shaz is right, An angel fish should not be in a 5G tank, and neither should the pl*co. Have you tested the water?