The Creepy Crawlies

(Unedited version)
Originally appeared in the April 2005 issue of
Tropical Fish Hobbyist Magazine

This month I get to talk about one of my very favorite aquatic topics, the freshwater invertebrates. Invertebrates very simplified are animals without backbones (the vertebra). Approximately 95% of animals are invertebrates; they include mollusks, crustaceans, insects, jellyfish, anemones and worms among many, many others.

Most of the invertebrates are very tiny, microscopic animals. You probably have quite a few in your aquarium already and may not even know it. For right now though, I'll talk about some of the more visible invertebrates.

The first invertebrates that most aquarists encounter in the aquarium are snails. These are part of a group of animals called mollusks, most mollusks look like snails, slugs, oysters and clams but they also include octopuses and squids. The first recorded animals kept for aquaculture were oysters kept in the 1st century B. C. by a Roman.

Unless you take special precautions to keep them out, they will often show up in your aquarium whether you put them in there on purpose or not. The snails most likely to show up are ramshorns, pond snails or Malaysian livebearing snails. Snails do not like very soft water as they can't develop their shells.

Ramshorns describes a number of species of snail and probably crosses. These are small snails whose shells are flat sided and curled in the shape of a ram's horn, hence the name. The can be tan, brown, red, or spotted and many combinations. They are probably the most common of the aquarium snails. They eat algae and are particularly useful for helping to keep the aquarium glass and surface areas free of some of the softer algae, though they aren't helpful for hair algae, or blue-green algae. These snails are hermaphroditic and will reproduce very rapidly in the aquarium and can become over populous. They lay their eggs in a little mass on surfaces in the aquarium. I've heard many reports of these snails eating aquarium plants. Personally I haven't had that problem. I have a lot of these snails in my tanks and though I have seen them eating plants and plant parts that are already failing, I haven't personally seen them attacking healthy plants.

Pond snails are similar to the ramshorns in regards to their brown colors, and often spotted. This is also a common name that refers to a number of different species of snail. These snails are similar in shape, having cone shaped shell. These snails usually come into the aquarium from local pond or lake waters. They can do well in the aquarium and are very similar to the ramshorn snails in regards to diet and reproduction. In a tank with ramshorns they don't seem to compete as well and ramshorns usually fare better.

The Malaysian livebearing snails have a long cone shape and are also sometimes called trumpet snails. The shells are usually spotted in tanks and browns. These snails, as the name implies, bear live young. They often live in the gravel going through it to find food. These snails can also do quite well in the aquarium becoming over populated. They don't have a reputation for eating plants that the ramshorns and pond snails sometimes get. Their shells are very hard and they can often survive snail eating fish better than the ramshorns or pond snails.

These are the most common aquarium snails. There are 2 basics areas of thought on these snails among aquarists. You either live with them (loving them or not) or work hard to avoid getting them, or trying to get rid of them. I happen to be one of those that live with them. I don't have trouble with them bothering my plants. There seem to be a lot of them in natural waters I've looked in so I don't think it's unnatural to have them in the aquarium. And I think they help keep away algae and are generally good for the tank. If you don't want them in your tanks there are several things you can do. First just try not to get them in the first place. This means making sure everything you put in your tank is absolutely snail and egg free, because just one little snail can totally populate your tank in no time at all. The other option if you already have snails is to use snail eating fish to try to eradicate them from your tank. Loaches from the genus Botia are often very successful at eating most snails, clown loaches being the most popular. These fish do sometimes have troubles with the Malaysian livebearers, due to their hard shells.

There are also other snails that are of interest to the planted aquarist. These include the apple snails, Columbian ramshorn snails, Japanese trap door snails and Nerite snails. These snails are larger and are used for algae control. They can be very attractive and some of them do breed in the aquarium. These types of snails are usually purchased through your local aquarium store or through mail order services. When purchasing apple snails, care must be taken. Some species will happily eat your plants. Pomacea bridgesii is the most commonly sold and is generally considered to be safe with most plants. Columbian ramshorn snails may eat plants also. Nerite snails are getting more popular lately as good algae control animals. There are fresh and salt water Nerite snails. While the smaller snails listed in previous paragraphs generally don't need extra foods. Some of the larger snails will fare better if given algae wafers, zucchini or other lightly cooked vegetables.

The next invertebrate that is of importance to the planted aquarium is the shrimp. These crustaceans are decapods meaning they have 10 legs. Crustaceans are animals that have a hard outer shell to protect their soft bodies inside and also include crabs, lobsters and many very small animals.

These little guys can be helpful in algae control and have become rather popular in the last decade or so. Shrimps used for algae control became widely known in the Western parts of the world after the publication of the 1st Nature Aquarium World book by Takashi Amano. The shrimp often seen in the book were dubbed Amano shrimp. At the time the book came out about the only shrimp available for aquarists in the United States were the ghost shrimp. Now several shrimp are available both at local aquarium stores and through mail order. These shrimp can generally be kept with most types of small fish. If the fish are big enough to eat the shrimp they usually will.

Still the easiest shrimp to find is the ghost shrimp. These little see-thru shrimp are often sold as feeders for larger fish. These shrimp are native to the US, and breed easily in the aquarium. The females carry the eggs and fry underneath their bodies until the fry become old enough to care for themselves. They look like miniature versions of the parents. In a heavily planted tank enough of the fry survive to keep a steady supply. Ghost shrimp will eat some types of hair algae and can be useful for other algae control in the aquarium. They can be predatory, and though they usually can't touch a healthy fish, they will eat anything they can catch, such as sick fish or sometimes fry.

The Amano shrimp (Caridina japonica) was the next shrimp to start becoming readily available. These shrimp are slightly larger and more colorful than the ghost shrimp. They are also good at eating some types of algae. Unfortunately these shrimp are very difficult to reproduce in the aquarium, though the females may be seen to carry eggs.

There are many new algae eating shrimp that are very recently being made available for aquarists. Most of them are small, and many have interesting designs. These shrimp include the tiger, ninja, bumblebee and crystal red shrimps, all from the Caridina genus and sporting stripped patterns. Cherry red shrimp (Neocaridina denticulata sinensis) are a small but beautiful bright red shrimp that are able to breed in the aquarium.

There are other invertebrates that can be in the planted aquarium whether wanted or not. Some are used as live fish foods. These include larva of flying insects, like mosquito larva, blood worms or glass worms. Other flying insect larva can cause problems in the aquarium. Dragonfly and damselfly larva are predacious and happy to eat small fish. They can be interesting in the aquarium but aren't really suitable to be kept with fish. I do occasionally get damselfly larva in my fish room. I've gotten both damselfly and dragonfly larva in pools and tubs I've kept outside.

Daphnia, cyclops and gammarus are small crustaceans that can also be introduced as food into the aquarium. Sometimes these types of invertebrates can come into the aquarium uninvited but don't cause problems. I have had some gammarus that had a particular fondness for eating aquarium mosses though. Some gammarus will also eat some types of hair algae also.

A number of aquatic insects are also suitable for a planted aquarium though not necessarily suitable for being kept with fish, in fact they usually aren't. Water scorpions, giant water bugs and some aquatic beetles can be kept alive in the aquarium. Many of these insects require live foods and will eat most of the live foods you can feed to your fish. If you have an interest in keeping any of these types of animals, be sure to research their food needs and your ability to provide them before acquiring the insects. Many of these insects also can fly and some can bite or sting. Field guides or web pages are often the best resources available for finding out more.

I have to admit to having a great interest in the freshwater aquatic invertebrates, and I have tried my hand at keeping quite a few. The water scorpion was one of my favorites, though they can be a bit gruesome in their eating habits. They grab their prey out of the water, such as a mosquito larva and suck the juices out of it like a vampire, until the prey becomes a limp husk. Water scorpions are said to be able to bite and can fly so keep the tank closed on these insects. I also once had some very attractive black beetles with yellow to orange spots. They liked to fly to the different tanks, I do keep most of mine open and I would never know where they would show up next. These insects don't necessarily do anything special for a planted tank, but can be just as interesting inhabitants as the fish, don't harm the plants and often can be kept in smaller tanks.

As you can see the world of aquatic invertebrates that can live in the planted aquarium is quite diverse. Though mostly used as consumers of various types of algae, these animals can also be very interesting tank inhabitants.

Questions or Comments?

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Welcome to the Jungle | Into The Forest | The Creepy Crawlies | A Clearing in the Thicket | Algae Eaters for the Planted Aquarium
North American Natives | Why things go wrong Pt 1 | Why things go wrong Pt 2 (Algae) | Algae Eating Shrimp | Lo-Tech Tanks
Welcome to the Fish Room | The Stemmed Plants | Mosses | A Livebearer Biotope | Planted Tank Social | The Genus Hygrophila | Cyanobacteria
Easy Plants | What I Did Last Summer | Decorations in the Planted Tank | Botany-An Introduction to Plant Biology | Botany-Anatomy of a plant
Botany-How Plants Work | Easy Rosettes | Going High-Tech | Floating Plants | Dealing with Success | Bringing the Outside In | Vallisneria
Hair Algae | Flowering Aquarium Plants Part 1 | Flowering Aquarium Plants Part 2 | Liverworts in the Aquarium | Elements of Design
Planted Aquarium Maintenance | More Mosses | Invaders | Ferns in the Aquarium | Setting up a Planted Aquarium
Seaweeds of the Pacific Northwest | Proserpinaca | Hardware for the Planted Aquarium | Rotala | Neocaridina Shrimp | Lo-tech Tank Tips

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