FSJF Ex-Situ Breeding

Learning more about freshwater fishes

Ex-Situ conservation is seen as a dead end by many colleagues. If habitats are destoyed or when alien species are the major driver of extinctions - how to return the Ex-Situ species into nature? Surprisingly it is often more fancy and more easy to raise money for reintrodcutions then for ground based conservation. While many species can be kept in captivity with little efforts, it is not so very easy to breed them without creating genetic bottlenecks and easily captive stocks become the victim of accidents. Furthermore, only nicely looking, small species are attractive for non-professional breeders. Therefore, Ex-Situ conservation correctly is only the very last action. But Ex-Situ might be the last chance to keep many species, maybe only for scientific reasons. There are actually only few Ex-Situ conservation programs in fishes but Ex-Situ will be a big thing in the near future. Therefore, it is time to learn more about the reproductive biology and how to keep endangered species in captivity. Fishes are kept at FSJF not to save the last individuals of their kind, but mostly for fun and to learn about their reproductive biology.

Several Critically Endangered and "Extinct in the Wild" species and populations are kept at the FSJF.

There are usually surplus fishes of several species. If you are interested to keep and breed some species, just contact me.

There are actually 20 species of freshwater fishes under my care, most of them in the outdoor facility. Almost all species breed regularly and several are here for many years and generations. During the winter months, all species are kept indoor in various aquaria and 300 Liter PVC containers between 4-12°C.

Types of outdoor tanks

PVC containers of 70 x 70 cm and 40 cm water depth. In these containers, broodstocks of the different Aphanius are kept.

PCV containers of 140 x 70 and 40 cm water depth which are used to keep Garra festai, Aphanius villwocki and Valencia broodstocks.

A large container of 100 x 125 cm and 40 cm water depth is inhabited by the Phoxinellus dalmaticus broodstock since many years.

Tanks of 100 x 100 cm and 60 cm water deep to breed Pelasgus, Pseudophoxinus, Tropidophoxinellus and Garra culiciphaga and also to keep spare fishes and juveniles of various species.

Furthermore, there are many small containers between 40 and 90 Liter for juveniles of the various species.

Well grown Aphanius apodus in August

Breeding technique of fishes at FSJF: All fishes kept at FSJF are plant spawners, which do not need gravel or flowing waters for reproduction. In all containers for the broodstocks, there is a hide, usually a plate of stone on two bricks and at least one willow stick which sent roots into the water and help young birds fallen into the tanks to climb out. In the tanks for the cyprinids, a considerable amount of filamentous algae, Ceratophyllum plants and the floating grass Glyceria fluitans are added. In some of the larger tanks, there are small Phragmites reed stands. The Aphanius and Valencia have only filamentous algae and a willow stick in their tanks. Furthermore, several Lymnaea snails belong to the standard inhabitants in each tank. I keep a stock of Lymnaea to avoid importing parasites from wild caught snails. All containers get at least four hours sunshine, usually more, and Aphanius tanks have slightly brackish water. There is no soil or gravel in the tanks but rotten plants and feces of the fishes and snails form a black mud after a while. This mud is removed at least once during summer, usually in July. If the mud is not removed, it results in low oxygen levels during later summer. At least 50% of the water surface is always kept free from waterplants. Water plants are removed partly from time to time but too much handling is avoided during the spawning season. Also the number of snails is limited.

All fishes kept at FSJF spawn spontaneously in their tanks and the dense vegetation limits the predation of the spawners on eggs and larvae. In the cyprinid species in which the broodstocks should be renewed or need some additions, larvae are transferred to empty containers each year. In the Aphanius and Valencia, the filamentous algae with the eggs are removed from the breeding tank and placed in an empty container. This is done all two weeks between May and July, in some species until early September depending on the hatching success. For some years, I had problems to get good numbers of eggs from some Aphanius species. These species preys strongly on their eggs, even when enough mosquito larva are in the tank. I use netted algae mops as spawning substrate successfully. All fishes are feed 2-3 times a week with Daphina, fish flakes, Culex and Chaoborus larvae and blood worms. Life food is seasonally plentiful at FSJF and since few years I actively breed mosquitoes in many small containers to have this food ready all summer long. All fishes also feed on algae and terrestrial insects which fall into the water. If possible, the stock of a species is divided into two or three containers to avoid losing all fishes by accidents.

The climate in Berlin allows the fishes to be outside between April and November/December. Then temperatures fall too deep and tanks freeze. In November or December all species are transferred to their winter rooms. There, fishes are kept without heating and usually at 4-10 C. Higher temperatures are avoided. To avoid losing all fishes by accidents, I separate juveniles from adults in winter. In species with good stocks, I keep half-grown, last year juveniles isolated from older spawners and add only few young spawners during summer.