Fish Tank

You may be asking yourself, “How could I possibly be unsuccessful with my tropical fish tank?”

The answer is simple: it’s not easy. You have to make sure you’re doing everything right because many things can go wrong if you aren’t careful.

This blog post will cover the five most common ways people fail when setting up their tropical fish tanks. If you want your new hobby to be successful and your pets to thrive- then read on!

Here are some of the most common mistakes people make with their tropical fish tanks:


The oft-heard aquarium rule of one inch of fish per one gallon of fish can easily lead new tropical fish tank hobbyists astray and down the muddy path of a dirty tank and potentially even running into issues with sick fish or loss of fish.
There are several factors that you should take into serious consideration before you inadvertently overstock your tropical fish tank.

Type of Fish

The type of fish that you select can have a significant impact on the health of your tank. There are several fish, goldfish, for example, who are not just major producers of excessive amounts of waste products, but they can often grow as long as 23-inches if they are offered the ultimate in living environments.

Without adequate space to grow to their full potential, the health of your fish will be seriously compromised.

Tank Space

Without careful and thorough research on the type of fish you add to your tank, you risk doing more than compromising their health. You risk losing them altogether if they are in a tank without enough space for them to thrive in and are in a tank without adequate filtration to help remove and dispose of any excessive amounts of waste products.

Before you purchase any fish for your tropical fish tank, you should have a solid understanding of how large the fish can potentially grow if provided with the right amount of space and other optimal living requirements.

It may work out to be a better option for you to have one large-bodied fish, like a goldfish, and several smaller-bodied fish like guppies if your tank is under 10-gallons.

When in doubt about the number of fish that can successfully thrive in your tropical fish tank, it is always a good idea to err on the side of caution.

Tank Space
A beautiful Fish Tank

Overfeeding & Under-Cleaning

The greatest risk to overfeeding your fish is not that they may gain excessive amounts of weight and risk their long-term health. Overfeeding hazards include the potential for that uneaten food to break down and release more nitrogenous toxins in the fish tank.

Directly related to the overfeeding issue, a failure to clean your fish tank by performing a water change (of at least 10%) regularly can negatively affect the health of your fish and your tank overall.

Consider the addition of a bottom-feeder or two to your tank for “clean-up duty” in your tank between water changes!

Rushing New Fish

In your excitement to introduce your newly purchased fish to their new home in your tropical fish tank, you may neglect to provide them with the time they need to get suitably acclimated to your tank. Simply dumping the fish into the tank will cause them to go into shock – which, in turn, could kill them.

The best methods of introducing your new fish to your tank involve patience and taking things slowly.

  • Place the plastic bag that the fish came home in directly into your tank, still sealed, for at least 30 minutes. This will allow the water inside the bag to match the water’s temperature inside the tank gradually, thereby avoiding any shock issues resulting from a drastic temperature change.
  • Once sufficient time has passed to allow the water inside of the bag to match the tank temperature, you should open up the bag and allow the fish to swim out at his own pace. Do not dump the fish out into the tank, as this could also stress the fish.
  • If you can, try to add more than one fish at a time to your tropical fish tank; this can help to reduce the chances that your new arrival will be singled out and possibly injured by other fish already in the tank.
  • Be sure that you have added new rocks, plants, and hiding places for your new additions to help avoid potential territorial issues with your other fish.

Sick Fish

An all too common mistake that all tropical fish tank hobbyists make is bringing home sick fish to their tank. These sick fish can potentially do more harm than simply dying after being added to your tank. They can also very quickly infect your entire fish tank – which can, in turn, contribute to a complete loss of life in your fish tank.

When you are shopping for your new fish to add to your tropical fish tank, you should be sure that you follow several guidelines to ensure that your new additions are as healthy as possible.

  • Try to purchase your new fish from a reputable seller. This will do more than ensure that you are buying healthy fish. Still, if something untoward does happen, a reputable seller is more likely to help work with you towards a rapid resolution to your problems.
  • Carefully examine the fish in the tanks before you pick out your new fish; examine them for signs of white spots on their bodies, frayed or droopy fins, or bulging or opaque eyes, and damaged scales. If a fish is exhibiting any of these signs, then you need to be sure that you avoid purchasing it; don’t buy it with the idea that you can potentially nurse it back to health – the odds are almost always not in your favor!
  • Once you get your fish home, you would be well served by placing them into an isolation tank on their own to ensure that they are, in fact, disease-free. Your isolation tank can be a simple 2-gallon tank with a hiding cave to provide the new fish with a little bit of privacy.
    If your new fish starts to exhibit any signs of illness, you should contact the person you purchased it from to discuss your options.

Mixing Mistakes

It is no secret that there are several types of fish that are incredibly aggressive and should be isolated from other fish at all costs to preserve their health and their life!

However, it remains a common mistake for new tropical fish tank hobbyists to build their tank with a collection of incompatible fish that territorially compete for space and food and attack and often greatly injure (or even eat!) other fish in the tank.

Oscars, for example, maybe relatively quiet, unobtrusive fish for several months in your tank; however, once they reach the full adult size, they may start to make a meal out of the smaller fish living in your tank. If you are going to stock aggressive fish, you will need to make sure that they do not cohabitate with smaller fish that could become a tasty treat for them!

Tip! An often overlooked and prevalent error that many fish tank hobbyists make is to neglect to place a thermometer and heater in their fish tanks. No matter the temperature in your home, you need to be certain that you monitor the temperature in your tanks to maintain the consistent temperature for your tropical fish.

Damsels, for example, require a temperature that moves no lower than 75 degrees and no higher than 82 degrees. While several crustaceans should be kept in a cooler tank where the temperature does not go over 76 degrees, you may require a water chiller to keep the water temperature down.

If you avoid some of the most common mistakes people make when setting up a tropical fish tank, you are more likely to find success and happiness with your hobby.