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Aquarium Invaders: Algae, Snails, Worms and Other Critters

By Jennifer Macke

 

Algae

blue-green algae
Blue-green algae (BGA): actually a form of bacteria, not strictly a form of algae. It is easy to remove, as it does not cling tightly. However, it is difficult to eradicate.

Aquarium algae are not really bad. In fact, algae have many of the same benefits as live plants in an aquarium: they produce oxygen and consume excess nutrients. If you can tolerate the appearance, algae is best left alone.

There are various kinds of algae you may find in your tank. None are a cause for alarm. For specific examples of algae types, and what they can tell you about your tank water, here are two good articles: Algae in a Planted Tank and Living with Algae.

Tanks that have been set up and running for a period of time (over 1 year) usually do not have serious algae problems, unless the water quality is poor. Here are some practical methods for reducing the amount of algae in your tank:

  • Reduce the amount of light. Move the tank away from the window, or run the aquarium lamp less.
  • Do partial water changes more often. This will help reduce the level of nitrates and phosphates in the water, thus providing less fertilizer for the algae.
  • Roll up your sleeves. Sometimes the only reasonable way to remove algae is to pull it out or wipe it off by hand. An aquarium cleaning pad will remove most algae, but some kinds require a straight-edge razor blade to scrape off.
  • Get a snail. However, snails tend to be somewhat selective about what kinds of algae they will eat, and some kinds of algae (such as black brush algae) will escape them entirely. Also, some large snails may pose a threat to your amphibians (see Species Mixing Disasters).
  • Allow some algae to grow in inconspicuous places. The algae that is allowed to grow will consume nutrients, thus making it less likely that algae will erupt in the places where you don't want it. Managing algae is NOT the same as weeding your garden, where you want to eradicate every last weed!
  • Be patient, and keep up with regular tank maintenance. After a tank is well established, algae problems usually subside.
hydra
Hydra: animals that resemble tiny sea anemones.

Do NOT use "Algae Destroyer" products. They are a needless expense, and nobody knows for certain if these products are safe for amphibians. Better safe than sorry, especially considering that the algae itself is harmless.

Do NOT try to solve an algae problem by getting a catfish or other algae-eating fish. Some of these have been known to injure or even kill amphibians. Newts and frogs have been impaled by the spines of cories and other catfish. Axolotls have gotten sores from being "sucked on" by sucker fish (plecos). For real-life examples of this, see Species Mixing Disasters.

 

Worms, Snails, and Other Critters

A healthy aquarium may be host to many kinds of organisms, including all sorts of invertebrates. They can range from microscopic to an inch long, and are often seen crawling along or sticking to the glass on the inside of the tank. If you have access to a microscope, look at some of your tank debris. You will probably be shocked by the variety of creatures you see. Some of them arrive in our tanks via live plants or live foods, others may get in as spores from local ponds, carried into our houses by wind or dirt.

Here are some of the common types of tank critters visible to the naked eye:

planaria
Planaria: small flat worms that cling to glass.
  • Snails. Small snails are harmless in an aquarium. Some people think they are a plague, but they cause no harm to newts. The only harm done by snails is that some will eat aquarium plants. But in most cases, small snails eat only debris and the dead parts of the plants. There have been cases of snails crawling on top of newts, or even laying their eggs on a newt. I have heard of these things happening, but never heard of any harm coming to the newt as a result. Some newts like to eat small snails. Large snails may pose some danger to newts. If they close down hard on a newt's foot or head, injury can result. For real-life examples of this, see Species Mixing Disasters.
  • Hydra: looks like a tiny sea anemone.
  • Planaria.
  • Limpets.
  • Tiny worms. Some kinds of worms may swim freely or make tiny tunnels along the bottom of the tank. Some of these are called "threadworms" due to their resemblance to tiny threads.
  • Leeches: live blackworms can come with small leeches, but these do not infect newts.

Most tank critters do not cause any harm. The only time you should be alarmed is if you see micro-organisms hanging directly on your newts. Newts can get ick and other external parasites, and these are cause for concern and treatment.

What to do if you have tank critters:

thread worms
Threadworms: tiny, thread-like worms. (Also, one limpet just below the newt's nose.)
  • Reduce feeding. Leftover food can fuel large outbreaks of tank critters.
  • Remove them manually by wiping them off and/or siphoning them out. If they are snails, pick them (and their eggs) off and throw them away.
  • Do a better job removing all uneaten food and waste products.
  • Do a better job adhering to scheduled water changes (at least 10% per week, perhaps more until the critter epidemic subsides).
  • Wait. In most cases, we only notice tank critters when they suddenly explode in numbers. If you wait, their number will almost always decrease as their food supply dwindles or they are balanced out by the growth of other micro-organisms in the tank.

Do NOT tear apart your whole tank and "clean everything" in order to get rid of the critters. If you do, you will need to start over with the process of cycling your tank, and you are likely to do more harm than good to your amphibians.

 

Additional Resources

© 2002 Jennifer Macke. Last updated May 10, 2008.