• Anisoptera - Dragonfly naiad


    Photo thanks to DiscusEden

    Name:
    Scientific name: Anisoptera
    Common name: Dragonfly naiad
    AKA: Dragonfly nymph, Mud-eye

    Country of origin:
    Australia wide

    pH:
    Temperature: cold water to tropical, depending on local conditions
    Hardness:
    Water flow:
    Oxygenation:

    Maximum size:

    Diet: Predators. They are capable of completely wiping out a population of shrimp in your tank, or taking small fish (up to 3cm) and of course eating any fry or shrimplets.

    Breeding:
    Eggs are laid in water, where they can remain dormant for 2 years until conditions are right.

    Tank companions:


    Notes:
    There are currently about 5680 species of dragonflies worldwide, of which 320 occur in Australia.

    Because they lay in water, there are 2 main ways that they get into your tank - through the introduction of plants with eggs on them, or by the dragonflies directly laying eggs in your tank. The first way is far more common with indoor tanks. A dip for 1-2 minutes in a 10% bleach solution (depending on the hardiness of the plant) can prevent this problem:
    http://www.aquariumlife.com.au/showt...o-remove-algae
    Do not dip mosses or subwassertang, which can melt. You can quarantine these in another tank (as you would with new fish) for at least 4 weeks.

    Both the adults & naiads have 6 legs. The naiads (the stage in the life cycle between egg & adult) have extendable jaws which they use to catch their prey. They can stay in the naiad stage for 2 months to 5 years depending on the species and conditions. They move through 12 larval stages before becoming adult.

    Naiads take in water through their rectum, to pass over internal gills. They can move very quickly (making them harder to catch) by expelling water through their rectum. They are also able to hide very effectively in tanks, particularly on dark substrate or in vegetation, and do not move continually around the tank, often sitting still for some time waiting for prey.

    If the tank is in a shed, outside, or in any other vulnerable position for getting eggs laid in it, people have successfully prevented this by making a cover of stainless steel fly screen for any gaps in the lids.

    To remove naiads from your tank, you can either squash them with your fingers (but be careful, they're prone to biting you when you get too close), or use biological warfare. By which I mean - add a larger predator, which is capable of wiping out the naiads for you. This is probably the preferred method, as it is very easy to miss naiads if you're hunting them yourself - it took me 2 weeks to catch 5 - and a jewel cichlid, for example, is on the job 24/7, and is also capable of finding & eating dormant eggs.

    Other suitable fish could be gobies (not small species), gudgeons, oscars or other large and aggressive cichlids.

    Because they often come into your tank on plants, they are rarely local species, or if they are, they are even more rarely local varieties. There is also the risk that the naiads could have picked up diseases in your tank. For both of these reasons, it is highly undesirable to catch the naiads and release them elsewhere. As dragonfly adults are predatory, and can predate of smaller dragonflies, by releasing an unknown species locally you could ba putting local dragonfly populations at risk in a number of ways - along with fish, shrimp and other critters.

    DE


    Relevant threads/ websites:
    Australian museum:
    http://australianmuseum.net.au/image/Dragonfly-nymph/

    More photos & discussion:
    http://www.aquariumlife.com.au/showt...weird-creature
    Comments 1 Comment
    1. corlis's Avatar
      corlis -
      Taxonomic clarification. Dragon flies and Damsel flies belong to the Arthropod order Odonata. The order is split into Damsel flies suborder Zygoptera and Dragonflies suborder Anisoptera. The example used comes from the family Gomphidae. Genus ? Doc
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