Blue Gourami with black head -- is he sick?  -02/20/08 I have a blue Gourami that is at least 3 or 4 years old -- he's (I call him a he but have no idea if he is a he or she) <Males have long, pointed dorsal fins.> in a 10 gallon tank along with 2 goldfish, 2 neon tetras, and 1 sucker fish. Has been in the same tank with these fish for about 2-1/2 to 3 years. No problems so far. <All this in a 10 gallon tank? Madness. The sucker fish is either a Pterygoplichthys catfish (average size 30-45 cm at maturity) or Gyrinocheilus aymonieri (only slightly smaller but infamous for its aggression). The Goldfish need a tank at least three times this size all by themselves. Oh, and Neons are schooling fish, and are only happy when kept in schools of six or more. While you might not have had problems yet, that's rather akin to a guy not killing himself at the first round of Russian Roulette and so declaring the game "safe".> We were away on vacation for the past 3 days and when we returned home last night, we noticed his head has turned black or maybe a really dark blue. It covers his entire head back to his first set of fins on either side. He is swimming around just fine and he is eating just fine -- not acting like there is a problem. The only thing that we did differently when we were away was that we: 1) fed them all using a 3-day tablet feed; <No need to feed fish for a 3-day vacation; in fact it is safer not to.> and 2) turned the heater on in the tank since we'd be away and the house would be slightly colder so the tank temperature was about 2 degrees F higher than normal. <How warm is this aquarium otherwise? How do you keep tropical fish in an aquarium without a heater? Unless your home is constantly at around 25C/77F day in, day out then these fish are not at all being kept correctly. Seriously: are you winding me up? Big fish in a tiny, unheated tank!! This sounds like someone trying to wind me up... everything is wronger than the wrongest thing that anyone has ever gotten wrong.> All the other fish are fine and he seems fine, I just do not know what this color is. Should I be concerned? <Very, very, concerned, though not specifically for the Gourami. Without a photo, can't say what's going on. Could be viral or even nerve damage (which affects the chromatophores) but this fish sometimes change colours thanks to genetic abnormalities.> If so, what should I be doing? <Buying a bigger tank and leaving the heater on all year around would be a start.> Thanks ahead of time for your help, Pam <Cheers, Neale.>