How many fish to a school?

[Ken Westervelt]

I am far from an expert on the aquarium side of aquaponics. There are certain kinds of tasty freshwater fish that school together. Arctic char, for instance. The problem is, I don't have a clue as to how many fingerlings I would need to get before they clump together and act like a school of fish.

This will probably not be my first tank I build, but it's good to know what options are out there.

[TCLynx]

I have noticed that with tilapia that if you only have a few in a tank, they don't seem as bold while if you have a larger number they do attack the food more.

Of course tilapia are also less aggressive to each other in a more crowded situation and tilapia do better with over crowding and poor water quality than most any other fish though they all do even better with good water.

I noticed some fighting with my catfish when I left only three big ones in my old sump tank but now I'm thinking it had more to do with the size of those fish than with the numbers since now in my big tank I have lots of fish and I'm noticing some injuries as if from fighting and there are several really big fish in there. I expect it is probably the size/age of the fish reaching maturity and trying to get territorial. I guess I need to figure out how to catch the big guys without hurting the smaller ones in the process.

[Richard Wyman]

Hi Ken,

An observation from my tilapia. I have only had my system going with other than gold fish for a month and a half, but I have noticed that fish in the bigger groups seem to grow faster. I had about 7 fish get into my sump and noticed that they were way more scared to come up and eat than the ones in the fish tank with about 20 of their siblings. The difference in growth in these few weeks has been huge. I finally caught the last of the sump fish and they are now eating better and growing fast.

This isn't really schooling behavior, but it does seem that more fish made for less stress and better eating from a very small size.

[TCLynx]

Well then it will probably need to be based on the type of fish as well as the filtration and tank size of course.

[Ken Westervelt]

I have heard that if there are not enough fish in a tank, they get ornery. It's more for the mental well-being of the fish than it is to see them clump together.

[TCLynx]

So are you asking specifically how many Arctic char you need to get them to demonstrate schooling behavior?

Is there a reason you need them to school?

It might take a fairly large tank to get all but the smallest fish to exhibit natural schooling. Perhaps a little more detail on what you are trying to do might help people search for the proper answers for you. I have a feeling most of the people on here would simply turn to some researching on the internet to see if there is info oh how many fish are needed to create a school and I'm sure that number is going to vary significantly by species.