Hi Ccooper! Well, you need to watch them out closely, since they cannot tell us what is wrong 🙂 and we need to discover it! Basically, all you need to do is change their water from time to time (be sure it never becomes yellow…if it is yellow is becoming acid! An you would not like to live in acid water, would you 🙂 ?)…also remember to get those drops (for pH and hardness) to put in the water (you can get them in the fish shop) – they are used to make sure that the water is good for the fish!…also be sure you feed them often, but not too much each time (each fish needs only a few flakes of food per day..otherwise the water will go bad fast!)…Another thing that you should do is check if you your aquarium looks like their “house” in nature: are there plants? sand? maybe some rocks to hide? some other fish for company? water bubbles? All of this will make your fish way happier! …Other than that just remember to look at it closely from time to time: see is it is active, looks good in colour, has no strange spots/stuff growing on it or even fins that are decomposing (fish are really sensible, and when something is wrong this should show!) and if they are not just go to the pet shop and they will have some medicines (fish get sick too, you know?)…That is it really! If you can do all of this right your fish will be really really happy!
That’s a much better answer than mine… I’m definitely not a fish professional!
All I know is when fish are floating (and still alive) then their food is too big and you need to mush it up more. And if they have white spots then they have ich and need medicine. And feed them and keep them clean 🙂
I think keeping fish happy is a pretty tough task – I’ve tried and failed 🙁 The only fish I managed to keep happy for a long time was a goldfish many years ago. I think that Sofia has covered most of the best points here, so I’d say follow here advice! I would add that it’s really important to try to keep the water at the right temperature for your fish, as even minor changes in temperature can upset some fish (others don’t mind so much). Fish are a brilliant pet but they require a lot of attention and care to be kept well and happy – good luck!