Cyclops, What Are These and Can These Freshwater Copepods Dangerous to Fish Fry in an Aquarium
Tuesday, July 24th, 2007QUESTION: It is kind of gray/white…head looks like a praying mantis…6 legs…long round tail…3 or 4 long antenna at the end of the tail…it stays at the bottom of the tank, and yes when I disturbed it, it wiggled, twitched and franticly swam to the surface. It gives me the hebby gebbies to look at.
I have never had live plants in my tank before, and never anything like this in the 15yrs I have fish (no fish in the last 5 yrs) until the bettas. Could it have come with the plants? Does it lay eggs? I’m I going to have more (very creeped out)?
If it is harmless to the fry, should I put it back in the tank with them? They will eat it? This things head is as big as they are…I’d rather flush it!!!
ANSWER:
It sounds more like this, which is a Cyclops (a type of copepod); they range in size from 1-3 mm. It is called a Cyclops because of the single eye spot. This female carries two packages of eggs near the base of her tail.
A little about Cyclops;
HABITAT:
Cyclops live in freshwater, such as ponds and lakes. They prefer areas of still water with a lot of algae.
THEIR PLACE IN THE FOOD CHAIN:
Cyclops are omnivores; they eat algae, small animals, detritus but not usually fish. But weak fry MAY be harmed by these copepods. Some species of Cyclops are not free-living, existing instead as fish parasites, but these are not common. Tropical and native fish enthusiasts utilize the cyclopoids as a high protein live fish food, especially for immature fishes, and in a fair twist of fate, some Cyclops species have been found feasting on larval fishes, particularly in fish hatcheries.
Cyclops are generally eaten by Phantom Midge Larvae and water mites.
REPRODUCTION:
The female Cyclops carries her eggs at the back of her body. There are fewer males than females present in the population, and the males are smaller. Females are often observed while swimming to have paired egg sacs, and most of the species are capable of explosive outbreaks when the water temperature and other conditions are optimal.
CONCLUSION:
Cyclops can also be intermediary hosts to the Guinea worm (which affects humans, but not generally fish) and fish tapeworm. These are rare occurrences for the Cyclops, and many aquarists consider them valuable as a fish food and even sell them. I would not be overly concerned with them for most aquariums as long as good aquarium cleaning methods, such as vacuuming are practiced. The exception would probably be with fish breeding. In this case, vacuuming gravel and rinsing off live plants in a mild bleach solution (live plants can handle a 25/1 solution provided it is rinsed off) would be in order. Keep in mind that these copepods do not like areas of high current and do like a lot of algae, so changing these conditions would go a long way in controlling Cyclops.
For more information and a picture, please visit: Aquarium and Pond Answers