Aquarium Fish Disease - Why do we get it

Aquarium fish disease and why healthy fish get sick is a problem that has plagued aquarium keepers for years.  Whenever we introduce new fish to an aquarium we run the risk of introducing disease or is it already in the tank?

There is a chance that when you introduce new fish, they will bring with them new parasites or diseases that your tank doesn’t have and if your fish have never been exposed to them there is a fair chance that they will have little or no immunity so yes new fish can bring disease to your existing fish and new fish can also catch diseases from your apparently healthy fish.

Your fish at some time in the past may have suffered an illness and developed immunity to it.  New fish introduced to the tank can then be exposed to an illness that they have no immunity for.  Using a quarantine tank and introducing new and old fish inside the quarantine tank can soon show you if that is the case without risking your whole fish collection.  Just use one of your cheaper existing fish as a guinea pig.

So having done the whole quarantine thing you should be fairly safe to introduce your new fish or are you?  Think about the set up in your existing tank.  If you’ve been doing it all properly, your fish are happy, they have a routine, some of them have staked out a small territory, they swim the same pattern every day, swim amongst the same plants.  You probably know which fish will be at the front of the queue at feeding time and which fish have a fight when the lights start to fade.  You have happy contented and healthy fish.

And then you introduce a new shoal, only four or five of them but still they’re the new kids on the block.  They want their own territory, they want their share of the food, they want to swim amongst the plants and they don’t know the existing rules.

Imagine if a new family moved into your street, started parking in your parking place,  took a short cut across your lawn on the way to work and even managed to buy the last pepperoni pizza in the store just before you got there.

Get the picture?  Stress.  One thing that fish hate is stress.  Stressed fish get ill.  Your fish and the newcomers can have been carrying a range of diseases for years without problems but as soon as they get stressed their immune system weakens and you have an outbreak of something awful in your tank.

So what to do?  Always introduce new fish in low lighting.  Turn off the lights, keep the room quiet so that they can get used to each other quietly.  If you have territorial fish in your tank, move some of the landmarks around before you bring in the new fish.  That way you can break up existing territories peacefully and make room for the newcomers.

Yes, use a quarantine tank but also do everything you can to reduce the stress for not just the new boys but also for your old faithfuls.  Think like a fish for a day and see the problem through their eyes and you will keep all your fish healthy and happy