Dystocia egg impaction

Anyone who keeps koi or goldfish will at some time come across a case of dystocia or egg binding, (sometimes called egg impaction), in a mature female. The condition will be evident in mid-summer, although in some instances things can go wrong in early spring.

The change in seasons, and thus, water temperatures play a huge part in egg development and the maturity of carp. As the daylight hours increase and temperatures reach the trigger point of 20 degrees C, those females that are mature enough to spawn will do so. In some cases spawning will take place in late summer if spring temperatures are unfavorable.

The ovaries have to have time to develop before spawning can take place, if this does not happen eggs will build up in the ovaries but will not mature. The process of egg production is continual, so even though the eggs are not mature enough to be spawned, more will be added as the season progresses, resulting in egg binding.

To a newcomer, observing carp spawning, is quite a brutal spectacle. Unlike salmon and trout, where the female lays her eggs and the male swims over the freshly laid eggs and deposits his milt (fish sperm, including the seminal fluid) over the top of them. The carps eggs stay in the ovaries and have to be almost beaten out of the female by strong physical contact from the male.

Several mature males will give chase to one female that is ready to spawn. After a long, hard chase the successful male, or males, will corner the female to prevent escape and more or less ram into her side, thus expelling the eggs.

There are implications for the fish due to this. As the eggs build up in the ovaries, the female is carrying an increasing load and in some cases infections can develop. Also, it may be that the female is not strong enough to survive the attentions of several amorous males. After spawning the fish should be checked as in some cases both females and males may need treatment for wounds incurred during spawning and most will at least need time to recover.

A female that is egg impacted will appear bloated, this will be soft to the touch initially and becomes harder as the season and the condition progress.

Treatment

If intervention is needed you can try the following;
If no signs of stress are evident, keep an eye on the female, let her go into the winter and if food is scarce, hopefully she will reabsorb the eggs as a food source. This may take up to two years.
Alternatively
Raise the temperature to 25 degrees C and keep the female at that temperature for a week at least. Try every other day to see if eggs can be hand stripped.The following can be used but are prescription only. I would not recommend them for the amateur, as milking a large female ripe with eggs is nowhere near as easy as the books and magazines would lead you to believe, if you are not confident/experienced in this please consult your vet.

    * CPE (Carp Pituitary Extract)
    * LH-RH (Luteinizing hormone/ Release hormone)
    * HCG (Human Chorionic Gonadotropin)

Implications

Egg impaction can lead to bacterial infection and septicaemia (systemic (bodywide) illness with toxicity due to invasion of the bloodstream by virulent bacteria coming from a local seat of infection. Also known as blood poisoning.). therefore the above treatments may need to be supplememted by antibiotics. Please consult your vet.