How to introduce new fish into aquaponics systems?

The successful introduction of fish into aquaponics requires a specific set of steps. This involves quarantining the newly arrived fish to protect the ones you are rearing and helping them acclimate to your aquaponics environment to ensure they thrive. This post aims to guide you in properly adding new fish to your fish tanks to avoid complications.

When should I add fish to my aquaponics system?

Adding fish to your fish tanks is a common practice among aquaponics growers. There are several reasons for doing so, and here are some of them that I can think of:

Harvesting of fish for commercial purposes

This reason is true for those growers who do aquaponics for profits. When the fish reach their maturation stage, they are ready to harvest and suitable for selling in the market. Since this is the case, growers will have to add new fish to their system to replace those that end up in their clients or supermarkets.

Balancing the fish-to-plant ratio

Another reason for adding fish is to achieve equilibrium between the number of your plants and the quantity of fish present in the fish tanks. The grow bed to fish tank ratio should, as a general rule, be about 1:1, meaning that the fish tank volume should be equal to the grow bed volume. If this ratio is not obtained, problems may arise that could affect the well-being of the aquaponics fish and plants.

Additional fish tanks

One of the advantages of aquaponics is its scalability. This feature describes aquaponics capability for expansion for productivity purposes. As you scale up the aquaponics setup, you will eventually add components, fish containers included. Consequently, you will introduce fish into these newly added tanks to fill them.

How long after adding bacteria can I add fish?

This situation applies to the process of cycling. Through this process, ammonia in your system is changed into nitrites and eventually nitrates, which your plants then use to flourish. The fish manufacture ammonia; it's a byproduct of their excrement. Without filtering the water, leaving the fish in their water will kill them and have no beneficial effect on the plants. By cycling, you can successfully introduce bacteria that convert ammonia and ammonium to nitrites and subsequently nitrates into your system.

Fish cycling can be achieved either with or without fish. The latter is the recommended procedure since ammonia is lethal to your fish, and adding them to your tanks while there are fish inside is counterproductive.

In fishless cycling, adding fish three weeks after adding the ammonia is recommended. This is because you can increase the quantity of ammonia you add to the system to promote bacteria growth without worrying about your fish dying. Cycling without fish also means immediately adding as many fish as you like to your system. Usually, you have to increase the fish level when cycling with fish gradually.

How should I add new fish into my system?

When you first receive your order of fish, it's not as simple as throwing a cooler or bag full of brand-new fingerlings into setup tanks and letting the system do its thing. You must quarantine the fish and carry out tempering procedures to acclimate them to the system's water supply. This step is applicable whether you are putting up fish tanks for the first time or simply introducing the most recent batch of fingerlings.

Quarantining new fish

The new batch of fish can be quarantined in brand-new tanks, but all subsequent additions must begin in a tank apart from the rest of the facility. It just takes one contaminated fish to introduce diseases and parasites that spread quickly and cost you thousands of dollars to treat, even when you purchase from the most reputable vendors. Before adding new fish to the stock tanks, keep them in a purging tank for at least one week and ideally two.


Even the first batch of fresh fish delivered into cycled and tested empty tanks needs to be tempered. Check the pH and temperature of the water the fish are packed in. You may need to spend several hours acclimating fish to the water because they can only tolerate one pH adjustment and two temperature changes per half hour. Use the container they arrived in for carrying or put up a different tank for tempering and fill it with the water used for hauling. To gradually acclimatize the fish without stunning them, replace 10% of the tank's volume with system water every half-hour.

Here are some steps that you can do to quarantine the newly-arrived fish for your aquaponics safely:

Receive your fish.

When fingerlings are shipped, they are containing a supply of oxygen. You must be accessible to receive your fish and get them acclimated into your system as soon as they arrive. This only lasts for a limited period (maximum 18 to 24 hours, typically less). This is also crucial if you buy fish from a local vendor because they frequently don't utilize pure oxygen when packaging seafood for local delivery.

Float the bags of the new fish.

Your fish need some time to adjust to the temperature of your water. The temperature can be adjusted by floating the bag in your fish tank. To make sure that the fish aren't moving more than 2-3 degrees, check the temperatures of the water in the fish tank and the water in the bags. The bag won't float if the oxygen is allowed to escape.

Determine the pH.

It's time to open the bag after you see a similarity in temperature between the shipping water and the fish tank water. Secure the bag with a clamp to the fish tank so it won't sink or leak shipping water into your tank before doing so. Check the pH in each container using an API test kit, a digital pH pen, or dip strips. The pH difference between the two should not be greater than .2 to.4. Add fish tank water to the shipping bag if the pH is noticeably altered. Depending on the pH changes, give the fish 30 minutes or more to adjust. Since the oxygen will be released, add a tiny air stone to the bag.

Observe safe water handling.

Although the water used to transport fish is typically clean, it is never sterile. Transport water may convey various germs, plant spores, creatures, and plant or fish infections, even with no purpose of sending along any problems. Some sellers use different salts, medications, or sedatives to transport fish. Avoid adding transport water to your aquaponic system for all the reasons above.

Transferring the fish

Carefully transfer your fish from the bag IMG 3114 into your tank using a small net. This is the ideal moment to take a close look at your baby fish because, depending on your tank's size, color, and clarity, you might not see much of them after they are in there. Placing a net over the top of your tank is an excellent idea to prevent problems with fish who believe they can fly.

No feeding of new fish.

Fish can go for several days without food. To allow them time to adjust and make sure the nitrifying bacteria are prepared for the fish load, don't feed them for a few days. Once you begin feeding them, take it carefully and start with a modest quantity to gauge their reaction. After 5 to 10 minutes, scoop out any unfinished food.

Was this post helpful?

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram