A sufficient supply of newly hatched brine shrimp is essential to successfully rear betta fish fry. The typical feeding regimen is to offer baby brine shrimp to betta fry twice per day until the young bettas reach the size at which they can eat normal prepared foods, adult brine shrimp and other forms of live food.
For a shrimp hatchery that is easy to build and very effective for harvesting baby brine shrimp, you will need the following items:
- two 2-liter beverage containers
- air line tubing
- rigid air line tubing
- silicone cement
- one 3-liter beverage container
To construct the hatchery, first take one of the 2-liter containers, which should be thoroughly cleaned, and cut off the top half. Drill a hole in the side close to the bottom of the container that is large enough for a piece of flexible air line tubing.
Cut off the bottom of the second 2-liter container — retain the bottom piece for use as a cover for the hatchery. The aluminum or plastic cap should be fastened securely. Drill a hole in the center of the cap just large enough to fit a 2-inch piece of rigid air line tubing through it. Insert the tubing so that it extends an inch on either side of the cap. Applying silicone cement (the same adhesive used to construct aquariums) around the tube will provide a water-tight seal. The cement must cure for 48 hours to reach full strength. Next, connect the flexible tubing that extends through the hole near the bottom of the first container to the rigid tubing in the cap of the second container, which is then inverted and inserted into the first.
Although this setup is reliable, it is probably wise to use a back-flow safety valve in the flexible tubing at the lowest point inside the container. These valves, which are readily available at any aquarium store, prevent water from flowing into the air pump should the pump suddenly cease operating, such as during a power outage. I prefer the valves without a check ball because that design permits easy siphoning of the shrimp through the tubing rather than using a kitchen baster to extract the hatch, as described below.
To use the hatcher, place approximately 1 teaspoon of brine shrimp eggs in the bottom of the inverted container. The quantity of eggs can be varied according to your needs. One teaspoon of eggs provides enough live baby brine shrimp for an entire feeding in my fish room.
Next, fill the inverted container to within 2 inches of the top (actually the bottom) and then add about 1 tablespoon of salt. Table salt is fine, but I use meat salt, and some hobbyists use one of the synthetic sea salt mixes formulated for marine aquariums. After connecting the air line to an air pump, the inverted container can be covered with the plastic bottom that was initially cut off.
After 24 to 36 hours, disconnect the air line from the air pump. Use a clothes pin or other suitable device to attach the tubing to something that will hold the tubing above the water line in the hatcher. To make it easier to harvest the shrimp, the entire hatcher, except for the neck of the inverted container (located near the bottom of the hatcher) is covered with a 3-liter container that has had the top cut off so it will fit over the 2-liter hatcher. The plastic bottom and label of the 3-liter container should shield the hatcher so that the only light reaching it is at the inverted neck.
Because brine shrimp are attracted to light, a strong source of illumination is placed next to the hatcher. After five to 15 minutes, the live brine shrimp will have accumulated in the neck of the inverted container. These can be harvested through the air line tubing by lowering the end of the tubing usually attached to the air pump below the water line in the hatcher, or from above by removing the 3-liter container and the hatcher cover and using a kitchen baster to remove the shrimp.
By constructing two of these hatching units, there will be a constant supply of live baby brine shrimp. Remember, you will want to provide enough shrimp for two feedings each day.