Ten Common Beginner Mistakes
By: Holly Harrington


Even a cursory look at the posts in the Forum Section underscores how confusing it is to be a beginner in this hobby. The questions come thick and fast, and in many cases, the answers contradict previous advice or long-held hopes – sometimes to a ridiculous extent. (No, despite what the fish store guy said, you can’t raise an Oscar in a 10 gallon tank.)

As a relatively new hobbyist, I am only too well aware of what beginners struggle with. And to that end, I offer these 10 common beginner mistakes as a map of what NOT to do. Read and heed. Your future fish will thank you.

1. Do NOT automatically trust your local fish store (LFS).

I almost wrote don’t trust them, period. But that’s unfair. There are knowledgeable and credible fish store owners and employees out there. They key is to weed through all those who don’t know, don’t know that they don’t know or don’t care that they don’t know. So test your LFS with questions you know the answers to. (Can I put neon tetras with African mbuna? The answer had better be NO!) And take notes of the answers and compare them to what you find online generally and on this site specifically. You might also try asking the same questions to more than one employee. The knowledge within a store will vary considerably. Try to find the “veteran” or the one employee who already has a tank or fish similar to what you want. In other words, find the planted tank nut at that particular store if that is what you are interested in.

2. Don’t start too small.

This assumes you have not yet bought your tank. Even if you have bought a tank, consider whether you might want to upgrade sooner rather than later. To many beginners, a 20 gallon seems manageable. And a 30 gallon tank seems gigantic. Trust me, it’s not. Your eyes (for fish) will quickly get bigger than your tank. And it’s easier to keep your water parameters steady with more water volume than less. Based on my own experience, I would consider a 40-something to 55 gallon tank a good beginner tank.

3. Inappropriate stocking.

This harkens back to the “can I keep an Oscar in my 10-gallon with a pleco and a school of neons?” This is where the poor LFS advice really comes into play. And this is where commonsense and online research comes in. Here is the single most important sentence to keep in mind when considering your stocking list: Not all fish can live together and not all fish should live together, and your desire for a particular fish will not overcome either of those. So, tetras need to be in schools, even if that means you have fewer types of different fish than you desire. Same for cories. Some fish cannot live with others of the same species not matter how much you want a school, as someone will end up dead. Some need open space. Some need plants and hidey-holes. Some need soft or hard water. Be kind to your fish and stock your tank appropriate to their needs. We want them to thrive, not survive. And if the welfare of your fish are not your highest priority when stocking, please walk away from this hobby and taking up golf.

4. Too many fish.

This is very much related to the above, but brings in the much maligned “one inch per gallon rule,” which most long-time hobbyists hate. I understand it is not a hard and fast rule, but I have to say, as a beginner, it at least gave me some sense of a yardstick. One good approach is to run your stocking list by the experts in forums for advice. Another is to start stocking slowly and stop while your tank still looks uncrowded. Wait a bit, let the tank shake out, and then decide if you can add something else. Patience is a virtue.

5. Ignorance of cycling.

There really is no excuse for this. There is an abundance of information on this site about what the cycle is, why it is important, how to start it and when to know it’s done. Anyone who throws a bunch of fish in a new tank with a “hey, some may die but that’s OK” or “but I ran my filter for two days, what do you mean that’s not enough?” should take up golf. See above. Cycling really isn’t hard. It’s about establishing good bacteria to “eat” the ammonia and the byproducts of that digestion so that your fish are in a healthy environment. And, no, clear water has no bearing on your cycle. The clearest water in the world may still be loaded with ammonia and kill your fish. Read up before you proceed.

6. Inappropriate testing.

In a nutshell, buy the liquid reagent testing kids. Many recommend API. Do NOT use the strips. They are too difficult to read and can lead you to making incorrect assumptions about your tank. Get accustomed to testing regularly, to begin with, for ammonia, nitrite and PH. Testing becomes less frequent as your tank becomes more established. But it’s your responsibility to know what the parameters are and take action if they are “out of whack.” Which also means you have to know what constitutes “out of whack.” Once you are cycled, your ammonia and nitrite should read 0 and your nitrates should register as something. (Anyone with 0 nitrates has an uncycled tank or isn’t doing the testing correctly.) The amount of nitrate you tolerate in your tank is open to lengthy and passionate debate. I personally do not let mine get above 20, usually more like 10. Some people prefer 5. Testing for PH leads me to No. 7

7. Using chemicals to adjust PH.

Ah, this was a hard one. I started out the queen of PH chemicals, but managed to learn my lesson without killing any of my fishies. In truth, PH can be somewhat confusing. Your fish have an optimum PH level, but many can tolerate both higher and lower levels, within reason. The best advice I got was to use your tap PH without modification, as long as it was appropriately buffered (had a KH of 3 or more) and thus would be relatively stable. If your PH is higher than you’d like for your fish (mine is), look into ways to add reverse osmosis water. I buy Drink More in big jugs and use is half and half with my tap to keep my PH around 7/7.2 in my community tank. I use it straight for my African tank, which is buffered with limestone and special coral substrate to push the PH up a bit. Everyone is happy.

8. Not changing water frequently enough.

There is some confusion about this among beginners as it seems that many LFS suggest very minimal water change schedules after the tank is cycled, perhaps to keep from scaring beginners away. I was told I only needed to do a 25 percent water change once a month. Instead, based on advice from here and elsewhere, I do 20-25 percent water changes twice a week. This forum is full of big supporters of frequent water changes. The statement I like the best is this: Freshwater fish like fresh water. Enough said.

9. Panicking over algae.

Yeah, just like sh*&, algae happens. A newly set-up tank seems to follow a pattern of algae, starting with a soft brown algae that caused me to panic but which really, in hindsight, was not a huge big deal. Yes, green spots will grow on the glass. Get one of those magnet thingees; they work great. There is a lot of information on algae, the different types and what to do about them here and elsewhere. My advice on the subject is not to panic. Do your research. There are some nice fish and shrimp that can help, and there are ways to balance nutrients and light to get it manageable. The subject is too lengthy for elaboration here, but suffice it to say, it’ll happen and you’ll deal with it.

10. Not planning for plants.

I have a planted community tank. I knew I wanted to go with a planted tank when I first set up the aquarium, but I was too overwhelmed with trying to care for the fish, that I didn’t want to think about it yet. I bought a bunch of plastic plants and I figured it would take me a while before I got to real ones. Nope. I started planting within a few weeks of getting the tank cycled. (Anyone want a bunch of plastic plants??) I then had to cope with a substrate that wasn’t conducive to plants. It can be done, but I would suggest that if you think you might do plants, invest in one of the substrates i.e. Flourite or others, and mix it in with your gravel from the onset. That way you are prepared. It’s very difficult to add it later and you are constrained, to some extent, on the plants that will do well in your tank without it.

I hope this information is helpful to those of you starting in this hobby. It can be confusing at first, but it’s also fun and interesting and, when all is said and done, profoundly satisfying. Good luck and happy fishies!

Rate this post


Please enter your comment!
Please enter your name here