Most people who are new or not into fish keeping say,” I don’t want big fish tanks, because they require more work!”
More water makes it look that way, but the truth is that larger tanks are easier to take care of.
What, but how?Imagine that the red dots are how much waste Mr. Fishy creates in one week- that’s 9 dots. On the left is the waste in a small tank and on the right is the waste in a big tank. The water in the small tank is more toxic because there’s more waste per part of water, but the big tank has less toxic water because there’s less waste per part of water.
What does this mean?
For the small tank, more water changes have to be done weekly to keep water safe for Mr. Fishy.
For the big tank, a smaller weekly water change is only needed to keep water safe for Mr. Fishy.
Here’s a weekly water test from a divided 15 gallon tank for two Siamese fighting fish (betta splendens):
Aside from pH (which should always stay constant), all of the toxins are at zero in my filtered tank. That’s always to be expected from any mature tank. But look at the nitrate! By the end of the week there is nearly zero nitrate, plants help but the size of the tank helps even more. If I didn’t change my water for 3 weeks, the nitrates would still be below 20 ppm- but I still do 10% water changes every week. I don’t have to worry about any catastrophes rapidly occurring.
But my fish doesn’t like big spaces!
If you get a bigger tank, fill it up with plants and ornaments to make your fish more comfortable. If your fish is not doing well in a big tank, it’s not because of water volume. A big empty tank is going to be scary for some fish, a small empty tank can be the same.
Tl;dr: Bigger volumes of water dilutes the daily/weekly amount of waste your fish creates, meaning less frequent/smaller water changes and more stability.