Overcrowding is not a pleasant situation. It is something that we want to avoid because crowded places suffocate us. This is also true with the aquaponics fish we rear in our systems. Too many fish is detrimental to the well-being of the aquatic animals that fill your tanks.
This article will explain what fish overstocking is and the health issues it brings.
What is fish overstocking in aquaponics?
Fish overstocking is when the aquaponics fish tank holds an amount of fish beyond its required capacity, or the ratio between your plants and fish is not already observed.
Typically, aquaponics growers, especially the newbies, are tempted to add more fish into their tanks, thinking this practice is good for the plants. However, in reality, by continuously adding fish and ignoring the proper fish-to-plant ratio, you are making your aquaponics system vulnerable to several issues. If left unchecked, an overpopulated fish tank could adversely affect your harvest.
It is a general rule of thumb to stock the correct number of fish in your aquaponics tanks. This ensures good fish growth and a profitable yield. In order for you to determine if you have an overstocked fish tank, consider the following indicators:
a. Oxygen level is below the required range.
b. Excessive amount of ammonia and nitrite in the tank.
c. The fish becomes aggressive and stressed.
d. You notice that there has been a stunted growth among your aquaponics fish.
Why does fish overstocking happen in aquaponics?
There are a couple of reasons for fish overstocking to occur. I have shortlisted them below for you to know them, and hopefully, you can protect your fish from getting too crowded.
a. Incorrect fish tank size: Generally speaking, large fish tanks are recommended because there is much room for adjustments and mistakes. In fact, larger volumes are better for novice growers since they provide more space for error and slower processing. I would recommend using a 250-gallon (1 000 liters) tank or bigger because this appears to be the most stable.
b. Improper stocking density: The number of animals kept on a particular unit of area is referred to as stocking density. This is the number of fish required per pound of water in aquaponics. Apparently, if your fish population is above the recommended stocking density of the tank, this could lead to overpopulation.
c. Unsuitable fish mixture: One known technique in aquaponics is sequential rearing. This practice involves rearing several species of fish in the same aquaponics tank. Suppose, the species of fish you decided to raise simultaneously have a different growth cycle. One species grows faster than the other, completely overwhelming them in numbers.
d. Uninformed aquaponics practitioner: This could be the fundamental reason why fish overstocking occurs in aquaponics. The practitioner needs to acquire knowledge to manage any aquaponics system. One of the things that need to be learned is proper stocking density.
When setting up an aquaponic system, practically every grower makes the enormous error of adding fish right away after filling up their nutrient reservoir. The new tank syndrome is the common name for this among growers.
I know that people frequently rush out to buy a large quantity of fish to supplement their diet because of the initial thrill. But let me tell you why this is entirely false.
In any fish tank, nitrifying bacteria require time to build a strong colony. Simply adding water from another fish tank that has been operating for some time will expedite the process. Additionally, you can utilize wood and stones from different aquariums. These objects frequently include pores on their surface, which provide a haven for bacteria to flourish.
Therefore, the next time you set up your aquaponics fish tank, you will need to wait four weeks before beginning to add any kind of fish.
What happens when you overstock fish in aquaponics?
First and foremost, an overstocked fish tank could increase fish stress. Overcrowding leads to discomfort giving your fish stress that is too much for them to handle. A small amount of stress can be harmless, sometimes, it benefits your fish, but too much of it will make them vulnerable to various diseases.
Aside from fish stress, overstocking of fish results in poor water quality. Too many fish leads to an overabundance of animal excrements inside the tank, making your water unsafe. Although some fish can endure challenging water quality, it is still advisable that you give them water in its pristine aquaponics condition.
When there are too many fish in the system, more ammonia is produced, resulting in higher nitrate levels. This situation could be fatal to your fish because nitrates at excessive levels could lead to nitrate poisoning.
If your tank is overstocked, expect low oxygen levels. Because your fish has gone beyond the required stocking density, they will eventually compete for the limited oxygen supply in your fish tank. Low oxygen levels in the fish tank cause fish to try to 'breathe' faster than expected, causing chronic stress and death.
How can you avoid fish overstocking in aquaponics?
a. Learn the growth cycle of your fish. By acquiring the correct growth cycle of your aquaponics fish, you can anticipate the time when they have to be harvested. By so doing, you can take the necessary steps to avoid an overpopulated fish tank.
b. Know proper stocking density in aquaponics. Your fish-to-water ratio (stocking density) would be 1 pound of fish per 5 to 7 gallons of water. (.5 kilograms per 20-26 liters of water.) This is a safe range for aquaponics fish stocking density.
c. Avoid stocking species of fish with different growth cycles. If you would resort to sequential rearing, I would advise you to take care of fish that grow at a similar rate.
d. Check important water quality parameters. As I have stated above, high nitrate levels or low quantities of dissolved oxygen are some of the red flags of fish overstocking. Therefore, you should periodically measure these parameters so that you can address them right away, saving your fish from any form of disease vulnerability.