10 Smart Ways to Use an Aquarium Catch Cup or Specimen Container

Have you ever seen those clear rectangle boxes hanging on the outside of tanks at your local fish store? This is the aquarium specimen or catch cup, one of the most versatile tools for fish keeping. It acts like a small, transparent bucket for observing fish, holding aquarium supplies, and a million other uses. Find out the top 10 reasons we use catch cups daily at our fish tank and retail fish shop.

1. Observation

When fish are zooming around the aquarium, or darting behind ornaments, it can be difficult to see them clearly. To get a better view, grab a few fish and set them up in a cup of water. The smaller space allows you to inspect the fish for disease symptoms, pick the healthiest individuals for breeding, or sort out male and female juveniles for sale. The clear, flat walls make it easy to photograph your favorite species.

2. Transportation

Although aquarium nets are fine for moving small numbers of fish from one tank, they can prove inefficient when you have large schools of fish to move. Your specimen container can be used as a temporary storage place until you catch all the fish. Then, move them together. To prevent fry from being eaten by predators, you can move them to a grow-out aquarium, or bring the pond fish indoors to enjoy the winter. You can also remove pest snails from one tank and feed your pufferfish aquarium.

3. Selling fish

You will need to pack your fish into bags if you intend on selling them at an aquarium store, fish club auction or online. Place the fish in the container. Once you have enough fish to go around, place them in a fish bag. Seal them with rubber bands. You can use multiple containers. The first container will hold the largest number of unsorted fish while the second one will contain the fish.

4. Acclimation

New fish and shrimp may have different water conditions than yours. You might need to slow acclimate them to aquarium water. If your animals are small enough you can allow them to adjust in the container.

1. Take the fish bag out of its bag. Once the fish have been soaked, pour some water into the cup. 2. To double the water level, add aquarium water from their new homes to the catch cup. (If the water gets too high, just pour some out of the container.) 3. After 15 minutes add more aquarium water until the water has doubled. 4. After 10 minutes add more aquarium water until the water has doubled. 5. Set the fish aside in a container and net them.

A length of airline tubing can be used to make drip acclimation, which is a more gradual process. You can calm fish that are running around in the catch cups by covering them with towels or darkening the room.

5. Breeding

By adding an airstone, check valve, airline tube, and an air pump, you can create your own DIY breeder container with a catch-cup. Keep the specimen container in the aquarium to keep it warm. Add the air stone to ensure the fish have enough oxygen. To increase the chance of a male and female mate, you can place one or two fish in each container. This setup is also useful for hatching fish eggs. You can also temporarily raise your newborn fry in a catch container without worrying about them (or any small foods they eat) escaping. To provide shelter for them, add a clump java moss and other live plants. You should also regularly clean the water from their catch cup with a turkey baster.

6. Isolation

In some cases, you might need to temporarily remove one fish from others. Female mollies, guppies and other livebearers who are about to give birth might appreciate a calm, peaceful environment for their babies. Setting up a “birthing room” will protect the fry from getting eaten immediately by bigger fish, and adding a clump of plants inside will help the newborns hide from their own hungry momma.

You could also isolate fish with unusual symptoms or injuries. Keeping them in a specimen container with an air stone allows you to monitor their status more closely and potentially treat them with medication if needed. For more information on treatment of fish diseases, read the full article.

7. Mealtime

We always recommend feeding many different fish foods to ensure your fish get a variety of essential nutrients, but it can be hard to juggle all those round jars and slippery packages. Use your catch cup as a portable food tray to carry everything as you move from tank to tank. You can feed frozen food by thawing the cubes in the water container. Next, use a pipette (or turkey baster) to squirt liquid into multiple aquariums. This same method can be used for live fish foods such as blackworms, baby brine shrimp, daphnia and infusoria.

8. Water Transfers

The catch cup acts as a mini-boiler, and we use it often to clean out an aquarium’s surface or replace water that has evaporated from a nano tank. If you want to test your water parameters using liquid reagents, scoop up some tank water with the specimen container and then use a pipette to fill the test tubes. Some hobbyists place catch cups in the aquarium, then attach the end of a hose to the container or point their Python hook at the tank while filling it. The catch cup gently overflows, protecting your plants from being damaged by the force of water.

9. Equipment Storage

If you use fish nets, alga scrubbers, or any other tool in your aquarium, a specimen container can be used to keep them from dripping all over the floor. Many people use them as extra storage space by hanging the catch cup on the side of the fish tank to keep their favorite fish food, fertilizers, and other supplies all within easy reach.

10. Planted tank maintenance

One of our favorite uses for specimen containers is during the maintenance of planted aquariums. Use them to remove duckweed and other floating plants that have taken over your aquarium so you can spread them to other tanks or feed them to your goldfish. While pruning, put your stem plant trimmings in the catch cup, and then replant them in the substrate to propagate them.

You now know that you must have a specimen container in you life. Get the Aquarium Co-Op Catch Cup. The walls are clear, so your fish can be easily seen. Additionally, the shatter-resistant plastic won’t crack if dropped accidentally. Plus, the extra-wide handle allows you to hang it on large fish tanks with thick walls.