The One Thing You Need to Know Before Buying an Aquarium

An aquarium fish, the panda cory catfish. Thinking of buying your first fish tank? Before you head off to the pet store, there is one thing you absolutely must know: it’s not easy. Setting up a new aquarium is far more complicated than you might imagine. It takes weeks and several tanks worth of water changes. Fish may (and likely will) die in the process. You will require multiple trips to the pet store. Your patience will be tested repeatedly.

Did I scare you? I didn’t mean to. I just want to help you avoid the mistakes we made when we decided a fish tank would satisfy our son’s desire for a pet. (Actually, that was mistake number one. If your child wants a dog or cat, a fish tank will never be a worthy substitute. You can try, but don’t be surprised if your child resumes his/her pleas for a furry friend in short order.)

If you’ve had fish in a bowl, as we did, you might believe that a tank is not all that different. You just buy it, fill it with water, get it to the right temperature, add some fish, and watch them live happily ever after. Right?

Not so much. It takes considerable time and effort to set up an aquarium. Before you decide to go down this road, do some research. This is where we failed. I’m not sure how, since we research just about everything before buying. Maybe it’s because we already had Bettas, which are extremely low-maintenance, bowl-based fish. In any case, we got a little impulsive, rushed our decision, and paid the price in lost fish.

What would we have learned if we had done our research? Here are a few of the more important lessons.

  • There’s something called the nitrogen cycle and it’s really important. Fish tanks require bacteria to manage food and fish waste. Without these bacteria, ammonia levels increase and fish die. There is a whole biological cycle that needs to be established in a new tank, ideally before you add fish, although having a few in the tank to create waste can help things move a little faster. There are tons of resources about the nitrogen cycle available online but I found this Beginner FAQ particularly helpful. (I really can’t stress this point enough: you must learn about the nitrogen cycle before buying a tank.)
  • Size matters. We bought a 10-gallon tank because we wanted a compact size. We were surprised to learn, after the fact, that many of the most popular tropical fish were too big for our tank. Key lesson: one inch per gallon, as in one inch of fish per gallon of water. For example, if your desired fish grows to two inches, you can have no more than five; if it grows to five inches, you can only have two. Buy the tank that fits your space, but do so knowing you might have to get smaller fish or just one or two big ones.
  • Test strips are worth the exorbitant cost. When setting up a tank for the first time, you will need to test the water a lot. I probably did way more testing than necessary, but you will need to check levels of ammonia, nitrate, nitrite, and pH on a regular basis to know whether your water is safe for fish. Test strips are not cheap but they do provide clear results. See the Beginner FAQ, linked to above, for more information on testing.
  • If you rush things, fish will die. It is really easy to convince yourself that the water is good enough and safe for new fish. Don’t do this. Wait until your ammonia levels are at zero or your fish will die. (Except Dave, our cory catfish, pictured above. He miraculously survived wild swings in ammonia levels while we got our tank set up. But he is a rarity. Do not assume your fish will be like Dave. Wait until your tank is ready.)
  • Get the right substrate.  This is a lesson we learned much too late. Our beloved Dave passed yesterday and the substrate we had is the reason. I edited this post to add this very important point. If you plan to have bottom feeders like cory catfish, get sand as a substrate. Gravel, which is the default for most people, damages catfish barbels (whiskers) and without them they cannot feed. No one at the pet store told us this and dear Dave is now gone, along with his buddy Jose and, soon I fear, their little friend Jebediah.
  • You have to tend to the tank every week. It’s not a case of set it and forget it. Fish need TLC like any living creature. Once you have fish living their best life in your tank, you’ll need to do weekly maintenance, including partial water changes, gravel vacuuming, and scrubbing tank walls. You may also have to deal with algae outbreaks that coat your aquarium decor in a yellowish-green slimy substance. If you have kids and expect them to help, realize that this can be a tough job for them to handle. And fish tanks do have bacteria, so you may not want your kids’ hands in there.
  • Fish tanks can be very noisy. Although known for their tranquil vibe, fish tanks can actually create a lot of noise. If you have an air pump to provide aeration, you may find it quite loud and prone to vibration. Even if you opt for a filter alone–which can provide more than enough aeration in a small tank–be prepared for the constant sound of water splashing. I actually like the sound, but the when we turn off the filter, we are shocked by just how quiet it gets.

After your tank is established, you have decide what types of fish to put in it. Many factors come into play here. You need to think about fish compatibility and personality. Some species can be aggressive and some like to school, requiring at least 5 or 6 friends to feel comfortable.

Feeding is another issue. Some fish like to hang out in the middle of the tank while others are bottom feeders, so you have to have the right balance and buy the right food for each type (and the right substrate, as noted above!) Some fish are a lot messier than others too, so be prepared to look at a lot of fish poop if you pick one of those. (Not to name names, but our platy is extremely messy, no matter how much or how little we feed her.)

And one final piece of advice when fish shopping: be wary of fish that look a little plump. Distended bellies can be a sign of disease or, in our case, pregnancy. We had two live-bearers (a black molly and the platy) arrive in our tank pregnant. Babies came, followed by a rash of infanticide since both species like to eat their young. My kids found it cool but younger kids might be horrified.

I’ve just scratched the surface here, but now that you know the realities of fish tanks, you can make an informed decision about whether to take the plunge into aquarium ownership.

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