by Danni Rodgers
(San Antonio, Texas, USA)
Many garden pool owners are eager to have fish. They may find the opalescent colors of Goldfish and Koi irresistible, or they may like the idea of having native fish in their pools.
The important points to remember if fish are to inhabit a pool have already been covered in the descriptions of pool models. What follows here are brief descriptions of those fish that can be kept in garden pools. Some rules and special tips for keeping fish are given to help you care properly for them.
The fishes described here are sometimes available at aquarium or pet stores. The European Bitterling, which is now naturalized in North America, is a protected species and may not be taken from natural waters in its native habitat. As a general rule you are not permitted to take fish from public or private waters without permission from state or federal officials or from the landowner.
Bitterling (Rhodeus sericeus sericeus): This Japanese strain of the Asiatic Bitterling is sold by pet stores. It is usually kept in garden pools. The European Bitterling (R. Sericeus Amarus) is a protected species and only rarely available from dealers.
Bitterlings, which have an iridescent, bluish green lateral stripe at the base of the tail, live in schools, and you should therefore get no less than four to six. They reproduce only if Unio or Anodonta mussels are present. Bitterlings need a clearly delineated area with a sandy bottom and a few plants in the shallow-water zone to spawn in. The mussels are best kept in a large plant container filled with sand (but no plants).
Brook Stickleback (Evcalia Inconstans): The obvious distinguishingfeature of this fish is the spines on the dorsal fin that can be raised. During the spawning season males claim territories that they defend against rivals of their own species and against other fish. Sticklebacks build nests on the bottom. The eggs are guarded by the male, who keeps waving his tail to move water over them and who defends them against enemies.
Since Sticklebacks are carnivorous and will eat anything that moves and is not too big to be swallowed, no more than two pairs should be introduced into a pool. Acclimation is problematic. That is why it is best to keep them first in an aquarium or in a separate pool. Otherwise the fish may languish and tend to get infested with fungi. Since the brook stickleback is prolific, it is best to give away the young fish.
Phoxinus Phoxinus: These are well suited for small pools. A population of five to seven fish is recommended. If the water quality is poor, the fish tend to develop tumors and fungal diseases. That is why it is important to monitor the nitrite-nitrate concentration regularly. A well functioning filter is essential. Better yet, connect the pool to a stream.
During mating time both males and females develop spawn blisters or vesicles on the body (looking like grains of cream of wheat). Spawn is deposited on stones and plants between April and July. The fry grow very slowly and do not reach sexual maturity until the third or fourth year.
Gudgeon (Gobio Gobio): This lively swarm fish is usually grayish green with a silver underside and dark rims on the scales. In small pools with other kinds of fish, introduce two to four fish; for larger ponds a small swarm (five to nine fish) is recommended. These fish rarely reproduce in garden pools. They keep the larvae of predaceousdiving beetles from getting too numerous.
Leucaspius Delineatus: These pretty fish with their bluish gray backs and silvery sides should be kept in small groups (at least five to nine fish). Depending on the size of the pool they may be quite prolific, laying their eggs in “spawn strings” between plants in shallow water.
Orfe (Leuciscus Idus): The wild form of this species is seldom kept in garden pools. But there exists a lovely cultivated strain, the “Golden Orfe,” that is golden or orange colored. These fish are highly recommended for garden pools because they eat insects (mosquitoes and other water insects). A small swarm of at least ten fish works out well. Golden Orfes need absolutely clean, oxygen-rich water because they are extremely sensitive to oxygen depletion (they gasp for air underneath the water surface).
If the nitrite-nitrate concentration is too high, they quickly develop open sores and tumors and need medication (available from pet or aquarium stores). They do not reproduce in a garden pool.