Tropical Fish Hobbyist

appearance. In fact, planaria are even in a class of flatworms called Turbellaria. Planaria I’ve seen in the aquarium have been in shades of white, brown, or green, but other colors can occur, some of which have patterns. Planaria often have a headlike area that is somewhat arrowhead-shaped, coupled with eye spots. The eye spots are light-receptive, but they are not true eyes.

Planaria glide across surfaces in the aquarium, and they generally eat much smaller animals that live on those surfaces. Some species of planaria will even ingest hydra and store the hydra’s nematocysts for their own future defense. They may also feed on fish eggs.

Planaria are not uncommon in the aquarium, but having large populations of them usually means that the aquarium is experiencing some pollution issues. Overfeeding, overcrowding, inadequate filtration, and insufficient water changes can all contribute to these types of infestations.

Hydra will attach to any surface in the aquarium, including a plant leaf such as this one, where they will wait to catch a meal.

Leeches

Just the idea of leeches often gives most people a case of the heebie-jeebies. Though a few leeches feed on mammals, most prefer a cold-blooded meal, while a few are scavengers, and still others eat plants. Leeches are usually introduced through plants or live foods that come from natural sources or ponds. I’ve also even seen wild-caught fish that have had leech infestations.

Leeches differ from planaria in that they are segmented and have suckers at both ends. This gives them the ability to move like an inchworm through surfaces in the water. Leeches are variable in color, but the ones I’ve seen on fish or in the aquarium have been a plain light tan or brown. The ones I’ve had the displeasure of being bitten by while collecting have been brown.

I haven’t had much experience with leeches on my own fish, but I have seen them in store tanks, on wild-caught fish, hitchhiking on things I’ve collected, or on things from someone’s pond that have been placed in quarantine tanks. For leeches that are infecting fish, the most recommended remedy is a saltwater bath for the fish. There are also medications available in most pet stores that may help for more severe problems. Since different species of fish have different

tolerances for both salt and medications, you should research your specific fish before treatment. The Internet and books are good places to start.

I should also mention that some people have aquariums specifically for keeping leeches. Some leeches can get quite large, and many have interesting colors or patterns.

Mosquito Larvae

Mosquitoes rarely show up in waters that have fish in them, but will very often show up—as if by magic—in almost any water situated in warm weather. This certainly includes any aquarium that has no fish in it, the water left in a saucer of a house plant, or any container that might have water in it that is located outside. Mosquito larvae can show up almost anywhere there is still or slow-moving water.

Both male and female mosquitoes ingest nectar, but females need blood to lay their eggs. Different species of mosquitoes like to feed from different species of animals, including, of course, humans. So after feeding off of you, a family member, or a guest, the female mosquito finds water in which to lay her eggs. They can lay up to 200 eggs in little floating groups called rafts. The eggs generally hatch in the next few days, depending

Though this animal has eye spots like a planaria, it’s actually a leech, with suckers on both ends.

on conditions, and then go through four larval stages. They hang head-down at the water surface, breathing through a siphon tube. In about one to two weeks the larvae turn into pupae. They can still move when disturbed, but not as well as when in their larval form. The pupae have no mouths, so they cannot eat, and they look like large commas hanging in the water. They emerge from this stage in just a few days as full-fledged adult mosquitoes.

The best way to get rid of mosquito larvae in an aquarium is to add a fish. There are very few aquarium fish that won’t be delighted to eat mosquito larvae. Shrimp seem to love them too, if they can catch them (and they usually can).