I see red spots on my fish, are they bad?

Question

My 3 goldfish just sudenly got red spots on them and they all got it at the same time. 2 days before that we got a fish that sucks on the walls eating algae, maybe that has too do with that or not. But if anyone knows somthing about that please answer!

Answer 1

I cant imagine that being anything good lol. look at an index of fish diseases, im sure there tons if you search on google or yahoo.com

Answer 2

If the red spots are round, it is very possible the algae eating fish had latched onto them several times, sucking away their mucus, leaving red "hickies".  You'll need to get rid of the algae eater.  Another possibility is that the new fish crashed the cycle, leading to ammonia spikes which would chemically burn the fishes' skin.  Water changes would be the best course of action.  Septicemia is another possibility, which is a systemic blood infection.  Medications may be necessary, but water changes would be the best start in case it isn't really an infection.

EDIT: Fin rot is caused by the same bacterium that causes septicemia, so it is very common to see the two symptoms together.  Triple Sulfa, Trisulfa, Furan 2, Maracyn 2, Kanaplex, and possibly Maracyn TC or TC Capsules would be effective against both.  Remove any activated carbon during treatment, and if using tetracycline or minocycline based medications, keep the tank dark, as these drugs degrade with exposure to light.