How to Build a Freshwater Predator Fish Aquarium

Predatory fish are fun, fascinating pets, but they’re not as low-maintenance as other aquarium fish. If you’re ready to make the commitment, invest in a large aquarium, as well as a filter, an air pump, and a heater. To create an attractive, enriching ecosystem, stock the tank with hiding spots and live or fake plants. While maintaining the environment takes some work, keeping your pets happy and healthy is well worth it!

Method 1
Method 1 of 5:

Setting up the Aquarium

  1. When it comes to tank size for predator fish, bigger is better. The exact size you’ll need depends on the species and number of fish you intend to keep. For instance, you can keep 6 cichlids in a 55 gallon (210 L) tank, but you’ll need a tank that holds at least 200 gallons (760 L) of water if you want to create a multi-species ecosystem. [1]
    • Be sure to keep your tank on a stand specifically designed for aquariums. A fully stocked tank can weigh as much as 10 pounds (4.5 kg) per 1 gallon (3.8 L).
    • New 200 to 400 gallon (760 to 1,510 L) tanks can cost thousands of dollars (U.S.). To save money, try shopping for aquariums at garage sales and secondhand shops.
  2. Purchase an external filter online or at a pet store that turns over 5 to 6 times the tank’s volume per hour. If necessary, use multiple filters to maintain your tank’s water quality. [2]
    • For instance, if you have a 100 gallon (380 L) tank, use a filter with a flow rate of 500 to 600 gallons (1,900 to 2,300 L) per hour.
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  3. Air pumps help keep the water in motion, but their main purpose is to add oxygen. Without an air pump, your fish could consume all the oxygen in the water and suffocate. [3]
    • Additionally, some species, such as African cichlids, like water with a steady current. When you’re browsing for fish, ask a pet store employee if they recommend a special pump or wave maker designed for fish that require a current.
  4. Control the tank’s temperature with submersible aquarium heaters, which are available online and at pet stores. The right temperature varies by species. [4] For most freshwater predatory fish commonly kept as pets, you’ll need to maintain a temperature of 75 to 85 °F (24 to 29 °C). [5]
    • Use this calculator to figure out the wattage your heater needs: https://aquariuminfo.org/volumecalculator.html . As a general rule, you'll need 3 to 5 watts per 1 gallon (3.8 L) of water.
    • You can either buy multiple submersible heaters, or invest in a single, more efficient one.
  5. Go with gravel or river pebbles from the pet store. Use a product that's specially marked for freshwater aquariums instead of using gravel from a hardware store. [6]
    • Before lining the tank, place the gravel in a sieve and wash it thoroughly with running water.
    • Sand usually isn’t the best choice, as it clouds up the water. However, some species prefer sand over gravel, so consult a pet store employee about the right option for your specific fish.
    • If you’re including live plants in your tank, you could also use aquarium soil. Be sure to purchase store-bought aquarium soil; don’t just use dirt from your yard or standard garden soil.
  6. Place plants , hiding spots, and decorative objects in the tank. Now it's time for some landscaping! Set up live or fake plants, caves, and other decorations to make the environment more enriching for your fish. [7]
    • Hiding spots are especially important if you’re keeping an ambush predator, such as knifefish.
    • Live plants are aesthetically pleasing and help maintain proper pH and oxygen levels. However, some predator fish, such as cichlids, like to dig up and kill plants, so fake alternatives might be a better investment.

    Providing light for plants: Unless you’re keeping live plants in the tank, you’ll only need a standard aquarium light so your fish will be visible. On the other hand, you'll need to invest in proper lighting if you're growing live aquatic plants. In general, you'll need 2 to 3 watts per 1 gallon (3.8 L) of water. [8]

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Method 2
Method 2 of 5:

Cycling the Water

  1. After you’ve lined the bottom with gravel, added plants, and placed hiding spots in the tank, fill it with warm water. To ensure your water is suitable for fish, test it with an aquarium test kit, which you can find online and at pet stores. [9]

    Amending water: If your tap water has high chlorine levels, purchase a dechlorinator online or at the pet store, and use it as instructed. If your tap water contains heavy metals, you may need to fill the tank with bottled or filtered water.

  2. Before adding fish to the aquarium, you’ll need to grow healthy bacteria that will help sustain the ecosystem. To start the process, either sprinkle fish food into the tank or add drops of store-bought aquarium ammonia. [10]
    • The fish flakes or ammonia drops will cause ammonia levels to spike. Then, bacteria that consume ammonia will start to grow. These bacteria will keep ammonia and nitrite levels in check and help prevent the water from becoming toxic. [11]
  3. the ammonia, nitrite, and nitrate levels regularly for 2 to 8 weeks. A few days after adding ammonia to the water, test it with an aquarium chemical test kit. Look for an ammonia reading of at least 2 to 4 ppm (parts per million). Test the water again every 2 to 4 days, and look for lower ammonia levels and higher nitrite levels. [12]
    • After the nitrite levels increase, keep testing the water regularly until nitrite levels decrease and nitrate levels spike. Within 2 to 8 weeks, ammonia and nitrite levels should stabilize at 0 ppm, and nitrate levels should be around 0 to 2 ppm.
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Method 3
Method 3 of 5:

Adding Fish to the Tank

  1. Before choosing fish, it’s always important to do your research. Never purchase fish on impulse; you must ensure fish are socially compatible and thrive in the same environmental conditions. In addition, be sure to read species descriptions or consult a pet store employee about how large a fish will grow. [13]
    • For instance, juvenile arowanas at the pet store might be less than 6 inches (15 cm), but they can grow to lengths exceeding 3 feet (91 cm)!
    • If want to include a mix of fish in the tank, ask employees at the pet store to recommend compatible fish. Avoid including small fish, which your predatory fish will attack or eat.
    • You could include aggressive and semi-aggressive African cichlids, tetras, and leopard bush fish in your tank, which all like similar water conditions. Provided your tank is large enough, add sizable non-predatory fish, such as a pleco (suckermouth catfish, which is an algae eater), giant danios, and red rainbow fish.
  2. Browse pet stores, research fish species online, and ask pet store employees for advice while you’re treating the water. Since it takes a few weeks to cycle the water, you have plenty of time to select the right fish for your tank. Once your chemical levels have stabilized, purchase your fish and bring home your new pets. [14]
    • When choosing fish, look for obvious signs of disease, such as blemished skin, white patches, cloudy eyes, or erratic swimming. Even if just one fish exhibits symptoms like these, assume that its tank mates are all potentially infected. If you spot any red flags, find another pet store.
  3. Before introducing your fish to the tank, set the heater to the recommended temperature, which will most likely be around 75 °F (24 °C). When the temperature is right, transfer the fish from their bags to glass or plastic containers. Place a container next to the tank, wrap a rubber band tightly around an end of a flexible tube, and run the tube from the tank to the container. [15]
    • Make sure the temporary container is only about half full. Gravity will siphon water from the tank to the temporary container through the tube, and the tightly wrapped rubber band will control the water flow. Drip by drip, the tank water will mix with the water from the pet store bag.
  4. Allow the tank water to drip into the temporary container and mix with the pet store water for around 30 minutes. Then scoop up the fish with a soft mesh net and transfer it to the tank. Repeat the steps to acclimate each of your new pets. [16]
    • To avoid introducing germs and parasites to your ecosystem, don’t pour the water from the pet store tank directly into your aquarium. Use a net to transfer the fish to your tank.

    Tip: If you have an established aquarium and are introducing new fish, shuffle around caves, plants, and other decorative elements. Switching up the surroundings will make the existing fish feel like they’re in a new environment, so they’ll be less likely to behave aggressively toward the new fish. [17]

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Method 4
Method 4 of 5:

Feeding Predatory Fish

  1. Most species of predatory fish require a diverse diet of frozen feeder fish or shrimp, mealworms, crickets, and commercial pellets. Specific requirements vary by species but, in general, offer at least 3 types of food per week to keep you predatory fish healthy. [18]
    • Ask pet store employees or check online for the dietary needs of your specific fish species.
  2. The right amount of food depends on the number and species of predatory fish in the tank. Most predatory fish commonly kept as pets need 1 to 2 mealworms, brine shrimp, or small feeder fish per day. Generally speaking, feed your fish the amount of food they can eat within 5 minutes. [19]

    Safety precaution: Some species of predatory fish have sharp teeth and powerful jaws. To prevent injury, lower food into the tank with a pair of forceps or tongs. [20]

  3. Giving your pets live feeder fish too often can promote aggressive behavior. Additionally, live feeder fish, which are usually guppies or minnows, are fatty and aren’t as nutritious as frozen options. If desired, offer them to your carnivorous fish once every month or so. [21]
    • Purchase feeder fish from a reputable pet store. When you purchase them, check the tank for cleanliness and look for sick fish. If you intend to regularly offer feeder fish, consider breeding your own in a separate tank.
    • If some of your predatory fish only like to eat live prey, try wiggling thawed, frozen mealworms or brine shrimp with the tongs to make non-living food more appealing.
  4. If you have any non-carnivorous fish, feed them commercial flakes or pellets once a day. Check your product’s label for the recommended amount of food to add to the tank per fish. [22]
    • Observe both your predatory and non-predatory fish when they eat to get a feel for the right amount of food. See how much food they can consume in about 5 minutes, and aim to offer that amount each day. Avoid overfeeding, which could lower the tank’s water quality.
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Method 5
Method 5 of 5:

Maintaining Your Aquarium

  1. Use a siphon and scrub brush to spot clean the tank regularly. Scrub any algae or other filmy growth off of the sides and corners of the tank first. Then vacuum up droppings, food scraps, and other debris with the siphon. [23]
    • Scrub first so you can vacuum up the matter you scrape off of the tank. To avoid damaging the glass, make sure no gravel gets in between the scrub brush and the tank.
    • Keeping an algae eater in the tank can cut down on maintenance. A pleco catfish is a good option, but be aware that common plecos can grow to a length of 12 to 24 inches (30 to 61 cm). Varieties that max out around 6 inches (15 cm) include the bristle nose pleco, peckoltia, otocinclus catfish, and farlowella.
  2. Siphon out the water into a bucket, then discard it. Fill a container with warm water (try to match the tank’s temperature), then add it to the tank. If your tap water needs to be treated, add a dechlorinator or any other amendments before adding it to your aquarium. [24]

    Tip: If the water is cloudy, chemical levels are off, a fish is sick, or a fish has recently died, change 50% of the water weekly. [25]

  3. Use your aquarium test kit to check the pH, ammonia, nitrite, nitrate, chlorine, and heavy metal levels at least once a month. Ammonia, nitrite, and chlorine levels should be 0 ppm, and nitrate levels should be less than 50 ppm. Note that, for some fish, nitrate levels should be below 2 ppm. [26]
    • For most fish, the pH should be neutral, or between 6.5 and 8.0. If necessary, add sanitized driftwood or peat moss to the tank, or adjust the pH with a store-bought amendment.
    • If ammonia and nitrite levels are above 2 to 4 ppm, change up to 50% of the water immediately. To quickly reduce toxic ammonia levels, purchase an ammonia aquarium amendment at the pet store.
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Expert Q&A

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  • Question
    How often should I vacuum my fish tank?
    Doug Ludemann
    Professional Aquarist
    Doug Ludemann is the owner and operator of Fish Geeks, LLC, an aquarium services company based in Minneapolis, Minnesota. Doug has worked in the aquarium and fish-care industry for over 20 years, including having worked as a professional aquarist for the Minnesota Zoo and Shedd Aquarium in Chicago. He received his Bachelor of Science in Ecology, Evolution, and Behavior from the University of Minnesota.
    Doug Ludemann
    Professional Aquarist
    Expert Answer
    Vacuum your fish tank every day if you can, but do it at least every other day. Start by using a scrub brush to loosen debris and algae. Then, vacuum out all of the debris and waste.
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  • Question
    Should I add ammonia to my fish tank?
    Doug Ludemann
    Professional Aquarist
    Doug Ludemann is the owner and operator of Fish Geeks, LLC, an aquarium services company based in Minneapolis, Minnesota. Doug has worked in the aquarium and fish-care industry for over 20 years, including having worked as a professional aquarist for the Minnesota Zoo and Shedd Aquarium in Chicago. He received his Bachelor of Science in Ecology, Evolution, and Behavior from the University of Minnesota.
    Doug Ludemann
    Professional Aquarist
    Expert Answer
    Add the ammonia to your tank before you ever put the fish in it. The purpose of adding ammonia is to help grow healthy bacteria that will support your tank's ecosystem. Put a few drops of aquarium ammonia into the tank. When the ammonia levels spike, good bacteria will eat the ammonia. Going forward, this good ammonia will help maintain the ammonia and nitrite levels.
    Thanks! We're glad this was helpful.
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  • Question
    Can I keep a predatory community aquarium?
    Community Answer
    It depends on the type of fish, but generally you would only want to keep one predatory fish in a tank.
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      Tips

      • Include predatory fish with various hunting styles in a multi-species tank. Look online or check with a pet store employee to find out if a species likes to stalk, chase, or ambush. Loading up on fish with the same hunting instincts could lead to territorial aggression.
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      • Consider adding aquatic invertebrates to the tank, such as snails. They can help keep your aquarium healthy.
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      • Sometimes, fish just don’t survive the shock of transitioning to a new aquarium, so don’t be too hard on yourself if a fish dies. Be sure to remove any dead fish promptly to avoid spreading disease.
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      Warnings

      • Many species of predatory fish can live for 10 to 20 years. Before building your community of freshwater predatory fish, be sure you’re ready for a long-term commitment.
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      • If your fish outgrow their environment, do not release them in the wild. Check if the pet store will take them back, or see if you have a responsible friend who’s interested in keeping an aquatic pet.
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      References

      1. ↑ http://www.tfhmagazine.com/aquarium-basics/aquariums.htm
      2. ↑ http://www.tfhmagazine.com/aquarium-basics/filtration.htm
      3. ↑ http://www.tfhmagazine.com/aquarium-basics/water--air-pumps.htm
      4. ↑ Doug Ludemann. Aquarium Care Professional. Expert Interview. 27 August 2019.
      5. ↑ https://aquariuminfo.org/beginner.html
      6. ↑ https://aquariuminfo.org/beginner.html
      7. ↑ https://aquariuminfo.org/aquascaping.html
      8. ↑ http://www.tfhmagazine.com/aquarium-basics/lighting.htm
      9. ↑ https://aquariuminfo.org/cycling.html
      1. ↑ https://aquariuminfo.org/cycling.html
      2. ↑ Doug Ludemann. Aquarium Care Professional. Expert Interview. 27 August 2019.
      3. ↑ https://aquariuminfo.org/cycling.html
      4. ↑ https://aquariuminfo.org/compatibility.html
      5. ↑ http://www.tfhmagazine.com/aquarium-basics/fish-selection--stocking-guide.htm
      6. ↑ http://www.tfhmagazine.com/aquarium-basics/fish-selection--stocking-guide.htm
      7. ↑ http://www.tfhmagazine.com/aquarium-basics/fish-selection--stocking-guide.htm
      8. ↑ http://www.tfhmagazine.com/aquarium-basics/fish-selection--stocking-guide.htm
      9. ↑ http://www.tfhmagazine.com/aquarium-basics/foods--feeding.htm
      10. ↑ http://www.tfhmagazine.com/aquarium-basics/foods--feeding.htm
      11. ↑ http://www.tfhmagazine.com/freshwater/feature-articles/the-killer-instinct-predatory-fish-and-how-to-keep-them.htm
      12. ↑ http://www.tfhmagazine.com/freshwater/feature-articles/the-killer-instinct-predatory-fish-and-how-to-keep-them.htm
      13. ↑ http://www.tfhmagazine.com/aquarium-basics/foods--feeding.htm
      14. ↑ Doug Ludemann. Aquarium Care Professional. Expert Interview. 27 August 2019.
      15. ↑ http://www.tfhmagazine.com/aquarium-basics/maintenance.htm
      16. ↑ https://pethelpful.com/fish-aquariums/Top-10-Mistakes-New-Fish-Hobbyists-Make
      17. ↑ https://aquariuminfo.org/beginner.html

      About this article

      Article Summary X

      To build a freshwater predator fish aquarium, start by getting a large, 200-400 gallon tank and lining the bottom of it with gravel, plants, and hiding spots for your fish. Then, install a filter, air pump, and heater to maintain the right water quality and temperature in the tank. Next, fill the tank with dechlorinated warm water, and cycle it for 2-8 weeks using ammonia drops or fish food. Finally, add compatible predator fish to the tank once it's cycled. To learn how to feed predator fish in your aquarium, scroll down!

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