Adding Fish To Your Aquaponics System


Whether starting up a new system or adding to your current stock there a few things to do every time you want to add fish to your system.

Verify Your System Is Ready

We covered cycling in our last blog which you can find here. I won’t belabor the point but you need to make sure that your system is cycling before you go to add fish unless you are cycling with fish. In addition, your water should be free of all ammonia and nitrites before adding any fish. Ideally, the pH will be around 7. Temperature range will depend on the fish variety you are adding.

Acclimate Before Adding Fish To Your Aquaponics System

Adding Fish Aquaponics Systems Requires Acclimation
Acclimate Your fish to your aquaponics system before adding them.

Fish are very sensitive to pH swings so you’ll want to start by testing the pH of the water that they came in against the pH of your system. It will hopefully be within a small change of each other but regardless you should acclimate your fish to you system water before releasing them.

The best way to acclimate fish to the temperature and pH of your tank is to let your bag of fish float in the tank water of your system. Drop a small airstone into your bag as well to keep the water oxygenated. About once every fifteen minutes add about a cup of water to your bag of fish to slowly adjust them to the pH. Once the temp and the pH of your bag match that of your system it is safe to release the fish into your system. I recommend that you add them by fish netting them out of the bag and not letting the outside water into your system water.

Quarantine Tank

If you are unsure about the quality of your fish and suspect that they may have a disease you will want to quarantine them before you add them to your system. You will want to acclimate them the same way we did above to your quarantine tank. A quarantine tank can be anything that is fish safe and holds water, no need to be fancy. You’ll need an airstone and some aquarium salt. You will want to salt the water prior to adding the fish and then use that water when acclimating your fish. If possible use the water from your system in your quarantine tank so the pH and temps will be nearly the same when you want to acclimate them to your system after treatment.

For treatment and prevention of disease, measure out three teaspoons of salt for each gallon of water in the tank. Using a small container, dissolve the salt in a small quantity of water taken from the tank. Once it is completely dissolved, add the solution to the tank. Let the solution get fully spread throughout the tank by the airstone for fifteen minutes before adding your fish. When using bath treatments, weekly water changes of 25% should begin one week after initial treatment. Do not add additional salt once bath treatments have begun. Most diseases should clear up in about two weeks time.

Once quarantined you will want to then go through the acclimation procedure with these fish before adding them to your system. You can use your tank as the holding vehicle and just add water from your system until the temps and pH line up again, Then net your fish into your system.

Final Thoughts

Once you have added fish to your system wait a day or two before feeding them. They will be stressed out from the move and likely wouldn’t eat anyways but hold off, in any case, to avoid further stressing them out. Observe them carefully over the next few weeks. If you are adding fingerlings to the system and got a bag with dozens or hundreds it is not uncommon for a few to die off from the move. Make sure to remove them quickly to avoid ammonia spikes. Always test after a die off to make sure water levels are still in the acceptable ranges and if not perform a 1/3 water exchange to get them back in line.


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