Almost everyone has kept fish at one point or another, whether won at a fair, brought home from school or bought at a pet store. Fish are relaxing, beautiful, and fun to watch as they swim gracefully around in a tank. Unfortunately, many of those fish do not live past the two-week mark after arriving home.

Most people who enter the fish-keeping hobby leave it after a few losses, without fully understanding why their fish passed away in the first place. I have been keeping fish for over eight years. I've successfully kept everything from to goldfish to freshwater tropical fish to marine community fish.

I believe that with a few tricks and a bit of research, keeping a healthy aquarium can be a very simple and enjoyable experience.

1. Overfeeding

Feeding is probably one of the most enjoyable and interactive parts of the hobby. Overfeeding is inevitably the most common issue that novice hobbyists encounter. Adding too much food into an aquarium can lead to water quality issues very quickly, especially since dry fish food can easily decompose. So how do you avoid this problem? There is no one correct answer since it depends on the number of fish, size and type of fish you have in a tank. The jar of food may say “as much as your fish can eat in 3 to 5 minutes," but I usually find that to be too much food unless you have a well-established community tank.

One guideline that I follow is: feed about 2-4 flakes per fish or 3 to 5 one-millimeter pellets per fish once a day (for fish that are between 2 and 4 inches). Another good rule to follow is to give your fish only as much as they can eat in 30 seconds and remove any leftover food with a net.

2. Adding too many fish at once

Stocking a tank with fish is a gradual task, one that can take multiple weeks. It's all too tempting to add all the fish you want to keep at once. The issue is that aquariums need time to grow enough beneficial bacteria to sustain a population of fish, through a process called cycling. In the aquarium nitrogen cycle, fish waste, dead matter, and uneaten food break down to create ammonia, which is highly toxic to fish. That ammonia is then broken down into nitrite (still very harmful to aquatic life) by beneficial bacteria (Nitrosomonas). The nitrite is then broken down into nitrate (harmless at low levels) by another beneficial bacteria (Nitrobacter).

As a rule of thumb, no more than one to three fish, depending on the size of the fish and the tank, should be added to a tank in a single week.

3. Inadequate water changes

Water changes are essential to a healthy water quality in an aquarium. They remove pollutants, detritus and excess nutrients from the water column. Water changes help improve water clarity, reduce undesirable algae growth, enhance growth, and promote disease resistance. How frequently you need to perform a water change depends on the tank size, type of fish and type of filtration you have. For most moderately stocked tanks, changing 25% of the water every month or 15% every other week is adequate.

For more heavily stocked tanks or tanks with more sensitive fish, changing 10-15% of the tank volume every week is recommended. You can also determine when to change the water by testing the nitrate levels in your tank and doing a partial water change once nitrate levels hit 40 ppm. When changing the water, make sure that the clean water being added has the same temperature and pH as the water in the tank. If you are using tap water, be sure to treat it with water conditioner to remove chlorine, chloramines and heavy metals.

4. Placing incompatible fish in the same tank

Keeping fish that aren't compatible is the same tank will lead to fighting, stress or, in some cases, being eaten by other tank mates. The factors that determine compatibility include temperature, pH, gender, maximum size, activity level, and temperament.

To determine whether the fish that you are planning to keep is compatible, I would recommend consulting a compatibility chart, Petco and Liveaquaria provide some pretty good ones. See: https://www.petcoach.co/article/friend-or-foe-freshwater-fish-compatibility-for-a-happy-tank/ Or: https://www.liveaquaria.com/PIC/article.cfm?aid=21

5. Unstable water temperature

A constant temperature within an acceptable range is imperative when it comes to the survival of coldblooded creatures such as fish. Temperatures that are too low will cause fish to stop eating since they aren't able to digest food. Temperatures that are too high can lower the dissolved oxygen content in the water and speed up the metabolic rate of fish. Rapid temperature fluctuations can lead to stress and make fish more prone to diseases. To prevent temperature issues, the tank should be located away from drafts and in a room that does not get hotter than 84 degrees Fahrenheit or colder than 60 degrees Fahrenheit. An aquarium heater is generally necessary for tropical fish since they prefer temperatures between 70 and 77 degrees Fahrenheit. When selecting a heater, a general rule to follow is 3-5 watts per every gallon of water, depending on how much the room temperature can drop in the winter. It is also very helpful to keep the heater tilted and near a filter or pump to distribute the heat evenly. Choosing a heater with a slightly smaller wattage can reduce temperature shocks and extend the life of the heater.