• Bugs and Worms in a Shrimp Tank - Description

    This article is written in order to help easy indentify some of the common bugs and worms in our shrimp/fish tanks with pictures and illustrations. They categorised under harmless and harmful to shrimps and fish.

    • Harmless: Daphina, Copepods, Nematodes(some species) and Rotifers.
    • Harmful: Hydra, Planarias, Nematodes(some species) and Leeches.

    Daphina, Copepods and Rotifers

    Figure 1: Daphina

    Figure 2: Rotifer

    Figure 3: Copepods

    Daphnia longispina (Figure 1) is pictured above. Water fleas are cladocerans, which are crustaceans under the arthropods. Commonly known as water fleas, they eat small organisms and other particles in the water. In turn they themselves are often eaten by larger creatures, for example, fish.

    This type of Rotifer (Figure 2.) named Testudinella are commonly found in our tanks which appears as small round hovering and darting bugs varies up to 0.2mm-0.5mm in size.

    Copepods and rotifers are mostly less than 1 mm long. Being so small, they can feed only on small food items like bacteria, diatoms or other unicellular forms. They usually end up as fish food if there are fishes in the tank and most are shrimp friendly though unsightly.


    Figure 4: Nematodes

    Nematodes are the most numerous multicellular animals on earth. Nematodes that feed on bacteria, fungi, and other nematodes, yet the vast majority of species encountered are poorly understood biologically. There are nearly 20,000 described species classified in the phylum Nemata. In size they range from 0.3 mm to over 8 meters. Nematodes are either parasitic or non parasitic. Example of a non parasitic nematode is the micro worms that most breeders cultured as fry food. Most nematodes are shrimp friendly. Some species of nematodes floats with the current or are free swimming


    Hydras are tiny animals, which are closely related to jellyfish. Green Hydras live in fresh water, such as streams, rivers, lakes, and ponds. They are very common.

    A Green Hydra can grow up to 30 millimeters long, but usually they are less than 15 mm. Hydras are found in shallow water, where they attach themselves to plants, stones, twigs, or other objects. Unlike their jellyfish cousins, they don't like to float around.

    The body of a Green Hydra is long and skinny. Just like jellyfish they have stinging tentacles. One hydra can have anywhere from four to twelve tentacles. Each tentacle has tiny bumps, called nematocysts. The nematocysts release a material that paralyzes another animal. Hydras use their nematocysts to capture prey, and for protection.

    Prey of Green Hydras includes aquatic insects, crustaceans (such as water fleas and scuds), flatworms, aquatic worms, fish fry, and other small creatures in the water. They also eat a certain type of algae, called Chlorella, which is what makes hydras green. Chlorella stays alive inside the hydra. Since algae makes its own food. The hydra lets the Chlorella make food for it.

    If a hydra needs to move (perhaps it's not getting enough food), it can detach itself and move like an inchworm. They are notoriously well known to kill shrimplets and fish fries in breeding tanks.


    Planarias are free-living, primarily carnivorous flatworms-with a three-branched digestive cavity and comes in a varieties of colors (White, Rusty Pink and brown). Planarias may eat other living, as well as dead, invertebrates, detritus or decaying organic matter. That is why sometimes even if you stopped feeding for a few days, the planarias do not died from hunger and may even attack freshly moulted shrimps and shrimplets when there is a lack of food. Planaria usually slides on the gravel and tank walls in search of food and or bury themselves in the gravel to hide away from the light.


    Leeches are annelids or segmented worms, and although closely related to the earthworms, are anatomically and behaviorally more specialized. They vary in size from 7 mm long to as much as 200 mm when extended.

    The bodies of all leeches are divided into the same number of segments (34), with a powerful clinging sucker at each end (although the anterior or front sucker can be very small). Most leeches feeds as blood sucking parasites on preferred hosts. If the preferred food is not available most leeches will feed on other classes of host. After feeding the leech retires to a dark spot to digest its meal. Digestion is slow and this enables the leech to survive during very long fasting periods (up to several months). Leeches tend to attach themselves to any living thing and suck the daylights out of them including shrimps and shrimplets.

    Bugs and Worms Part - Treatment: The second part will be looking at some effective solutions and prevention we can apply to our shrimp tanks.

    • Australian Museum 2003
    • Hydra: Chlorohydra viridissima
    • Introduction to the Rotifers
    • Marine Crustaceans of Southern Australia
    • Planarians.org
    • What are Nematodes?

    Article Copyright: simcb