Live-Bearing Tooth Carps (Viviparous)

The reality that fish can bring forth their young alive has usually been a source of amazement to the uninformed. This startling reality is most likely responsible for more individuals taking up the hobby than any other factor. Whilst it’s true that the young are born alive, they’re not born fairly in the exact same sense as mammals.

The egg is the medium utilized by all live-bearing animals to pass on life and perpetuate the species. In the case of mammals the fertilised egg attaches itself to component of the female where it develops, drawing sustenance from her bloodstream, until it’s ready to enter the world. The period of gestation is consistent with each and every species.

But with live-bearing fish this isn’t so. The eggs are situated in the egg duct where they’re fertilised. Upon hatching, the young aren’t instantly delivered, but remain until they reach a stage of development, equivalent to the young of egg-laying fishes that have absorbed their yolk-sacs, and turn out to be totally free swimming. The young are folded once inside the mother, and are delivered singly. They soon straighten themselves and swim to any plant or rock that provides them refuge. When initial seen in the aquarium they’re about a 0.25 inch lengthy, which is a lot larger than those of the majority of species that lay eggs to be developed externally. Their large benefit is naturally the protection of their mother’s body until they’re equipped to meet the outside world.

Unlike mammals, the period between fertilisation and birth isn’t standard, and is considerably influenced by temperature. As an average, this period is between four and five weeks at a temperature of 75°F. When the temperature is dropped the period increases considerably. At 68°F it might take as lengthy as 11 weeks prior to delivery. A temperature in the region of 80°F induces rapid incubation of the eggs, and tends to make more robust fry.

Sexing is no issue, even to the inexperienced eye, as the novice can discover to distinguish the distinction in a couple of minutes. At birth, and for a couple of weeks after-wards, it’s impossible to sex, but as the male nears maturity the anal fin becomes more pointed and lengthens into a rod-like projection in no way resembling a fin-this is known as the gonopodium. The gonopodium is normally carried backwards close against the body, but it’s capable of movement in any direction or angle. The female retains a regular anal finch

You’ll recognise courtship by the alert appearance of the male, who, with fins erect, chases the female until a suitable chance presents itself for a fast thrust of the gonopodium.

Livebearers rarely seem to require any artificial means of inducing them to breed. On the contrary, they generally breed quicker than accommodation could be discovered.

Females can have up to eight broods from one fertilisation; as a result it’s not essential to mate them instantly after the initial brood. One school of thought suggests that if a male is put with a female within 24 hours of delivery of her young, the next brood will probably be influenced by the last male, but I don’t totally accept this view. It’s unlikely it’ll have any effect on the subsequent broods until after the fifth. Much better control of fertilisation could be maintained if the sexes are kept in separate tanks to stop cross breeding among comparable species.

A ‘ripe’ female is one that’s nearly ready to give birth. You are able to determine this by the dark crescent-shaped area on the female’s body close to the vent, referred to as the ‘gravid spot’. This is accompanied by a fattening of the fish when viewed from the top or side. After just a little practice it’s feasible to judge from these two elements roughly the time of delivery.
The number of young in a brood is influenced by size; the larger the female the greater number of fry per brood. This has no effect, nevertheless, on the size of the babies, which are aU born approximately the exact same size.

Livebearers are cannibalistic, and have no hesitation in devouring their own young as soon as they’re born. You are able to stop this by putting the ripe female into a tank by herself with lots of fine leaf foliage (Myriophyllum) in which the young can take refuge. Remove the female as soon as the young are born.

It’s not usually feasible for the business man to be on hand to remove the female when it would do most great, and to overcome this difficulty I advise you to use a maternity cage or breeding trap. The object of the trap would be to restrict the female to a portion of the aquarium by means of a Perspex cage, the bottom of which is made up of a series of rods spaced to ensure that newly born fry will fall via out of reach. When suspended from the aquarium side, the top edge should be 1/2 inch above water level.

A fantastic benefit of the breeding cage is that more than one female could be put into it simultaneously with out fear of one eating the fry of the other, as they’re delivered.

Another technique of safeguarding the young would be to insert two pieces of glass or Perspex in the tank to form a trough, with a gap of 1/8 inch along the bottom edges for the fry to fall via. A bracket made from sheet lead, notched to hold the glass will maintain it in position, or make a trough totally of glass using Araldite as an adhesive.

The benefit of such a trap is its simple installation when needed.

Usually snails should usually be present in the tanks, if feeding dry food, to eat up any surplus. Snails require access to air, so don’t fill the tank to such an extent that there’s no surface area between the trap and also the side of the aquarium.

Handling of livebearers when they’re near the time of delivery might trigger them to give birth prematurely. Premature young have not fully absorbed the yolk sac, which could be seen attached to the belly. Few premature births survive, but if the yolk sac is extremely little they might be saved by adding one teaspoonful of salt to each and every gallon of water.