Offering a 2-week x 2-pair spawn of Nothobranchius guentheri «Zanzibar TAN 97-02» Blue (Tanzania). The image used above is for illustration purposes only. This species can be successfully bred and maintained as long as you act in accordance with all the recommendations listed below.
For breeding purposes, the aquarium size should be at least 30 – 40 litres for a breeding group of a few pairs. Males can be at times aggressive towards their kin’s and in that case, it is better to separate them or transpose them into larger tanks before casualties are allowed to occur. After having spent some time in a tank, each male establishes his own territory, which he eagerly defends against intruders. Relatively speaking, this species is not as aggressive as some other Nothobranchius but they certainly can be aggressive to the point where females can suffer fatal damage. Wild specimens generally tend to be more aggressive than aquarium-raised specimens of the same species. In general, the best way to deal with aggression is to raise and breed them in groups (e.g. 5 – 6 males and 10 – 12 females) and do not at any time separate them. Taking one male out of a group and placing him back say a week later will assuredly create trouble. Raise them together as fry and as they grow and mature remove only those that aren’t needed or that aren’t wanted until all that are left in the tank corresponds to the chosen breeding group. In a group, the aggression is spread around although the less dominant males and smaller females will be picked on and the displaying amongst males will draw their attention away from the females to some extent. Another advantage of group spawning is a larger gene pool but of course, this does also mean that larger tanks are needed.
As a spawning substrate one should foresee a box wherein a 10 mm thick layer of coir or neutralized peat moss can be introduced. This device helps, to limit the use of peat moss to a strict minimum, to concentrate the eggs and to avoid contamination of the eggs with waste from the tank. Always use freshly boiled and properly rinsed peat moss because the egg revenue is lower when using recycled peat moss. You can leave the fish to spawn for about 2 weeks, after which the peat moss is removed, gently pressed to reach the known tobacco consistency (peat moss containing eggs should not be allowed to dry out too much) and put in a plastic bag for further incubation.
Nothobranchius is a substrate plough spawner. The reproduction of the species can also at times cause trouble. Not that they don’t produce enough eggs, healthy females can have a large egg production, but the hatching percentage can be at times very variable. The eggs are small in size, from 0.6 to 0.7 mm, and can withstand much abuse. The eggs are a little bit adhesive and can be seen in the spawning substrate with a bit of effort.
The fish can be maintained and reproduced in ordinary tap water with a pH 6.8 – 7.8 and a total hardness between 10 to 20 dGH. During the day, the maintenance temperature would preferably be maintained in the vicinity of 24°C – 26°C and could be allowed to drop at night to around 20°C. After two weeks of spawning, the spawning substrate containing the eggs is removed, slightly dried and poured into a plastic bag which is then sealed, keeping at least 3/4 of the bag volume filled with clean air. The eggs are transparent but not very difficult to localize in wet spawning substrate. The moisture content of the spawning substrate containing the eggs should not be allowed to fluctuate too much during incubation. The sealed and labelled plastic bags are kept in a dark place where the temperature will be maintained around 24°C – 25°C. The incubation time is very dependent on the storage temperature, substrate moisture, and other factors. All further steps are now a question of patience. The average incubation time of the eggs lasts between 3 to 4 months and requires several hatching phases before one can ascertain that most eggs contained in the spawning substrate have hatched. We recommend incubating the eggs at least 3 months (see the collection date on the sticker); it is only after this period that good hatching results can be expected. Only wet the eggs when they (most of them) are fully eyed up.
Hatching the fry happens by pouring either aged or freshwater onto the spawning substrate containing the eggs. The hatching water should, however, be chilly, having a temperature between 16°C – 18°C. The addition of salt (1 teaspoon of sea salt per 3 litres of water) will help combat velvet disease and increase the longevity of the baby brine shrimp that one will have given as food. While wetting the spawning substrate add some Paramecium (approx 10 ml) to make sure the fry have their first food right after hatching. At hatching time, the water layer, which comes to cover the peat moss, can easily have a depth of 5 – 8 cm. With such a water layer you should have good hatching results after between 1 to 24 hours of immersion. This large water volume renders faster water changes superfluous and dissolves to a greater extent any salt and waste products. In addition, at the bottom where the eggs await hatching, the necessary oxygen shortage by which the developed fry break through the eggshell is created at a much faster paste; not entirely developed embryos remain however quite in their resting stage. Light aeration of the water can happen but is not absolutely necessary. The newly hatched fry are small and should first be fed with Paramecium and then – Vinegar Eels or Banana Worms (this is indeed the case if the first supplied freshly hatched brine shrimp nauplii are too large to be eaten by the fry). Rearing of the fry usually does not cause any further problems. The small fry grow fast and after nearly 2 months the first fish become sexually mature. Fry mortality rate is high if one does not change water on a very regular basis.
In order to obtain a good egg production, it is recommended to separate sexes during growth and wait until the fish have grown stronger and larger before starting to breed. If this important aspect is systematically neglected, after some generations, the females will grow much smaller than males and remain behind in strength. Seasonal fishes, because of their high metabolism, require a strong, adequate and regular food supply in order to keep their energy-demanding egg production at full capacity. If food is in short supply, the fish will soon perish. It is also recommended to separate genders at the moment the males become sexually active and display their first colours. Smaller females and later males stand then better chances to grow to full size. Nothobranchius is quite sensitive to radical water changes and drastic pH variations. The water changes have to be much more partial and also more gradual. Because of the very high metabolism in this species, it is absolutely necessary to provide on a daily basis strong and sufficient live foods, as otherwise, the fishes will be wasting away very rapidly.
The fishes can grow up to approximately 2.5 – 3 cm (females) and 3.5 – 4 cm (males). Providing correct conditions the life span is around 12 – 18 months.
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