How Much Is Too Much?

Since fish can take a while to grow into an edible size, one question that people keep asking is “how much fish can I have in a single tank?” Well, this can be a tricky question and it depends on your acuaponic system.

Too many fish can lead to a lot of trouble if your are not careful

The first thing is stress. Having a lot of fish crowded in a single tank can be stressful for them and that can affect their growth and their health. This can cause your fish to stay small, even if they are well fed. This is a survival technique in a lot of species that compete for space.

As always, the biological filter (or any other filtering system you use) will have a lot more work to clean the additional ammonia generated by your fish and the pump will need to move more fluid than before. Did I already mention feces? The bottom of your tank will have to be cleaned more often, in case you don’t have a “pre-filter” to get rid of the sludge.

Even if everything you have in place is enough to handle all your fish and solids, there is the possibility of a pump or power failure, which can lead to a massive death. And getting rid of many death fish is not exactly fun.

With proper care, you can have a lot of fish in a single tank

So… with all this problems, why will somebody have more than a few fish? In aquaponics (well, is more an aquaculture thing), more is better. Having more fish in the same space can lead to a higher yield in fish and vegetables, since the fertilizer will be more than enough to grow more plants.

Also, having more fish crowded in a single tank disrupts reproductive behavior, which can be really troublesome with some species. Dealing with a horny fish roughing up everybody else is not easy, and having a lot of younglings competing for food can make things more complicated.

About the stress, well, living in the wild is a very stressful thing, so I wouldn’t worry too much about that.

Well then, how much is too much? I will have 1 fish in every 3 gallons of water. That gives them space to be a little comfortable and will give you several fish per season. This is not a recommendation; is an option. You can always scale your filter up to deal with the additional ammonia and the aquaponic system to handle more plants.

As always, testing is a must. If you are a newbie, start with a few fish and let it grow slowly. After all, you are dealing with living creatures and, even if they don’t kick and scream, they are alive and feel pain. Don’t be so mean.

Of course, this is for home acuaponic systems. Commercial installations may need the additional fish to make some profit, so is a different point of view.

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