TO BE OR NOT TO BE A WORM
By Jim E. Quarles
Few people really know that what is referred to, as bloodworms are
really not worms at all. They are from the family Chironomidae, in the
order Diptera. Class Insecta.
They are larvae of the non-biting midges. In Singapore over fifty
species have been recorded. Not all the chironomid larvae are red in
color. The surface types are greenish others are white, only those that
contain hemoglobin are red, this is where they get their name bloodworms.
The chiromid larvae and pupae are highly nutritious and nourishing and
are one of the staple food items in the ration of many fishes in the
natural environment. The importance of chironomid larvae as live food for
tropical fish culture is well known in Asia. All carnivorous fishes, such
as Oscar's, discus, Siamese fighting fish and most all the cichlids will
greedily devour them when they are offered as part of their diet.
In studies done by hatcheries
in Asia discus have been shown to grow
Faster and spawn earlier when fed with bloodworms. With bloodworms as a
supplementary food they gain better weight and the growth rate is more
The supplies of chironomid larvae are mainly imported and this is
partially true for the United States. The natural breeding sites for
chironmid midges are diminishing due to the rapid urbanization and
modernization of wetlands. Also it should be noted that supplies of
bloodworms have at times been unreliable and seasonal as the larvae are
subjected to the fluctuation of the populations.
CULTURING CHIRONOMID LARVAE
As long as a half-century ago attempts to propagate the bloodworm under
laboratory conditions have been carried out in many countries. The chief
difficulty is the inability to induce swarming and mating of the
chironomid midges in captivity.
The life history of bloodworms involves four stages: Egg, larva, pupa,
and the adult midge. The eggs are laid in amass which is enveloped by
transparent mucilage. Each egg mass contains between fifty and seven
Under tropical conditions incubations periods varies from 24 to 48
hours. The newly hatched larvae are not more then 1mm long but they
measure up to 10-=16 mm when they reach the last stage of the larva
period. They molt four times before it reaches the pupae stage. Then after
two days it comes to the surface of the water and emerges as an adult.
As adults they live only three to five days and mating and oviposition
takes place during this period.
The Nutritive Value.
The nutritional value of bloodworms is considered to be very good.
Chemical analysis shows that bloodworms contain about 9% dry matter and of
this about 65% is crude protein, ten percent is crude fat and about 10
percent is ash. They contain 15. % Nitrogen free extract. They are also a
good source of iron for fish since they contain hemoglobin in their blood.
Culturing Blood Worms
In Hong Kong, chironomid larvae are grown on chicken manure. But to
produce blood worms in large quantities the cost must be taken into
consideration. Such a project is not practical on a limited scale and most
hobbyist would find it far cheaper to by the frozen product.
Are They Safe For Discus?
The answer seems to be yes frozen, but it is not recommend that live
bloodworms be fed if you are not sure of the media on which they were