Pond fish

If the installation of fish in a pond requires some minimum precautions, in practice success is very often at the end of the road! Here are some tips for a lively pond!

The creation of an outdoor pond often aims to install a flock of fish that will give life and color to the stagnant water. To facilitate the success of this project, a few tips are important to remember.

First of all, the water must obviously be clean! The use of pesticides or fungicides should be avoided in the vicinity of the pond!

The second main principle to ensure a serene life for your fish is to encourage the installation of insects. The planting of aquatic plants will encourage the arrival of this providential guard provided that a space in shallow water is provided where the larvae can develop without having to suffer from the attacks of the fish!

Generally, it takes a good month between the time the pond is dug and the introduction of the fish so that the pond is populated with sufficient microbial fauna for a harmonious biological balance. When all the ingredients are present, it is time to look for new residents. And there, the choice can be difficult!

Indeed, not all fishes agree! Some of them eat each other while others live together quietly. To be sure of your choice, it is better to avoid mixing species.

For smaller ponds, the best choice is undoubtedly the goldfish. These small fish (maximum 40 cm) live perfectly in schools. The species has many varieties: red, black, orange and white, with simple fins or undulating fins (the comet).

For larger ponds, it is possible to choose a mixture of goldfish and Koi. These two species cohabit perfectly if there is enough space. Be careful though: Koi carp are imposing. It can reach up to more than one meter in length which implies to calculate the number of fish per cubic meter!

Other possible species of pond fish are the sarasa (20 to 23 cm) which is characterized by its red back and white belly or the shunbukin (20 to 23 cm) which can be recognized thanks to its multicolored blue, black, red, orange and white body, the ide (35 to 50 cm) with its bright orange back or the tench (30 to 60 cm) with its pretty green dress.

The water birds of the pond

The reception of water birds, whether wild or domestic, requires prior preparation of the pond. A few simple arrangements are necessary to facilitate cohabitation and maintain biodiversity.

When creating an ornamental or swimming pond in the garden, the first reflex is to create an "ideal" space for the fish without necessarily worrying about the birds.

This is a mistake, because it is obvious that even if domesticated waterfowl are not allowed, the pond will inevitably attract wild birds.

Indeed, a watering place is often the place where many birds converge such as geese, ducks, herons and other swans.  They find there something to drink, but also something to bathe in and something to eat.

To prevent these birds from destabilizing the biotope, a few small adjustments are necessary. For example, by installing wire mesh over the shallow water of the banks, sheltered areas are created for the tadpoles. Without this precaution, the future frogs have no chance of escaping the voracity of passing birds.

If the pond is often exposed to waterfowl, it is also a good idea to cover the shoreline with pebbles or a plastic mat. This protection of the floor in shallow water will prevent silt from forming. When a duck comes along, it will not be tempted to dig for food, which will prevent the water from being contaminated by suspended silt. 

If there are many wild birds, it is also more than recommended to choose large fish species to avoid that they end up as an appetizing meal for the birds. If the pond is to be used for domesticated ornamental birds, the same considerations apply. It is also advisable to add a screen around the pond to prevent the birds from escaping and to prevent predators, such as foxes, from doing their business.

The choice of ornamental bird varieties is immense. 160 species of ducks are domesticated among which we find the mandarin ducks, the shoveler ducks, the gadwall ducks, the whistling ducks, the pintails, the carolins. In addition to these species, there are other birds such as teals, geese, and domestic geese...

All these domestic birds require little maintenance. Depending on the case, a food supply will be necessary, especially if the pond is small. Deworming twice a year helps to keep the birds in good shape and to keep the water healthy.

The insects of the pond, necessary for its balance

The success of a pond in the garden is based on the establishment of a complex ecosystem where insects play an important role since they are, in spite of themselves, a real "pantry" for the fish and amphibians of the pond!

At the slightest water hole, life swarms! If the fish and plants can obviously be put in place by the hand of man, the arrival of the insects is entirely (or almost entirely) the work of nature! And we must admit that nature is well done, since it only takes a few weeks at the most after the installation of a pond to see many species of water flea insects flocking in.

The main purpose of these insects is to provide a food source for the fish and amphibians in the pond. This is true if the pond has been well designed of course! Indeed, to ensure the survival of these insects, you must think of providing them with a small shallow corner that will keep them safe from adult fish. This small attention will also be welcome to provide a shelter for fry and small fragile fish.

Generally, the first to colonize the wetland are mosquitoes. These insects, which are very unpleasant for the fragile skin of humans, are a real godsend for fish, since their larvae, which lie flush with the water, are a king's meal for any well-constituted fish.

Apart from mosquitoes, many other species will gradually colonize the space, including the very graceful dragonflies, but also detritivores, phytophagous, insectivorous predators, not to mention certain exclusively aquatic species such as dytics and water bugs.

All these insects will attract amphibians and birds to the pond. Although all these insects promote biodiversity without compromising the pond's internal balance, some species should be closely monitored, such as the caterpillars of the water lily (a small butterfly) and the water beetle (a small beetle) whose larvae shamelessly devour the leaves of aquatic plants.

The same goes for aphids, which are best drowned from time to time by immersing the infested leaves in water to avoid carnage on the water lilies! With one simple action, the greedy aphids will become a real feast for the fish!

The great variety of insects attracted by stagnant water is a guarantee of balance for the pond. To preserve it, it is obviously imperative to ban the use of pesticides in the garden!

Aquatic insects

Apart from dragonflies, few insects catch our attention when we observe a body of water. This is a big mistake, because this little six-legged world is very fascinating...

Specificities of aquatic insects

Many insects live in contact with water. Essential to the ecosystem of ponds, pools and rivers, they help maintain a natural balance in these particular environments. Some of them, such as mosquito larvae, feed on bacteria or small particles suspended in the water, others, such as dragonflies or dytids (Dysticidae), carnivorous, eat living prey, and still others, such as Hydrophiles or Coleoptera, voraciously devour aquatic plants.

These insects have the specificity of seeking out wetlands, they are fond of banks, some live under stones, others find shelter in dead branches, others will spend their entire lives in water. Thirteen orders of insects share the aquatic environment but only five have species that live exclusively in water, such as the dytics and water bugs.

In their larval state, many insects develop underwater; this is the case of the dragonfly which will take two years to emerge from the water to take flight or the mosquito and the gyridinae beetles.

A well-oiled food chain

As we have seen, aquatic insects feed in a variety of ways and thus participate in the ecosystem of the water bodies where they live. But they are also part of a very organized food chain, and serve as food to many predators. Flying insects are of particular interest to birds, but also to amphibians. The larvae and insects living constantly in the water will be consumed by carnivorous fish, ducks or herons.

Some common aquatic animals

• The gerris, better known as the water spider. Very common, it glides gracefully on the surface of calm waters with small hairs waterproofed by a thin oily film present at each end of its legs.
• The nepus, otherwise called bug or water scorpion is an insect that moves at the bottom of stagnant water, it is very common in these environments.
• The dragonfly and its variants. Well known, it spends its youth under water in the larval state to transform into a formidable flying predator during its adult life.
• The mosquito is also born and transformed in water, going through four stages of growth (egg, larva, nymph and adult) in a record time varying from 10 to 15 days depending on climatic conditions and species.
• The notonect or water bee is a water bug that swims backwards and whose bite can be painful if handled without precaution. 
• The linear ranate resembles a phasma, it is a species of bug that uses its front legs to capture its prey that it will empty with its powerful rostrum.
• The fringe dytique is a common beetle that can exceed 3cm. It can attack larvae of amphibians or fish.
• The mayfly is well known by its short life and its larva which is aquatic.
• The chironoma is a small insect resembling mosquitoes but which does not bite. The adults gather at the end of the day to form characteristic swirling clouds at the time of reproduction. Its larva, the bloodworm, is well known especially to aquarists.

Mayflies, the nourishing manna of the pond

Thousands of mayflies take flight over the pond in the heat of May. For a few days, a few hours. Without eating, they are present for a moment, to ensure the perenniality of the species.

The mayfly 

2 to 3 cm long, it can be recognized by its arched body, its slender abdomen prolonged by thin rings, its vertical wings, its reduced antennae. The mayfly belongs to the large group of Ephemeroptera, along with hundreds of cousins difficult to differentiate from each other as they are so similar.

All over the world they are found in thousands of species, under all latitudes, except the coldest. Except also Iceland and some Pacific islands. Their life is divided between the aquatic world, for their larvae, and the air, for the adults.

An ephemeral life

The adult mayflies fly away in spring, for a few hours, 2 to 3 days at the most. Their so short life is devoted only to the reproduction, as soon as emerged the males fertilize the females, the long front legs allowing a firm catch. Immediately, the mayflies will lay eggs.

For certain species, the eggs will be released in full flight, others will pose them on water or just on the surface, others still will fix them to immersed substrates.

A single female will emit 500 to 6000 eggs. Then will disappear, without having even sought to nourish itself. Its digestive organs and mouth parts, regressed, do not play any more any role.

Long life to the young

The eggs of Ephemera will give birth to small larvae with the entirely aquatic life. They breathe with external gills, 2 rows of 7 arranged along the abdomen. Their shape, aspect, differ according to the species, and allow determinations with a magnifying glass. Just like the antennas, more or less short. The larvae are remarkable for their long and fine cerci, 2 to 3, extending their abdomen. To feed they have crushing parts, and are for the majority detritivores.

But some species have adapted to other food regimes, scraping the substrate, filtering, sometimes predatory. They need about twenty moults, during several months, to reach a pre-adult stage, the subimago, rapidly transforming into a formed adult.

From mountain streams to marshes

Mayflies are found throughout the world in a wide variety of species and habitats. From mountain streams to calm rivers, from ponds to marshes, all wetlands welcome them. The larvae can be burrowing, crawling, swimming... They disperse according to the currents, carried in the plumage of the birds. Adapted to many environments, extremely prolific, they play an essential role in aquatic ecosystems. Bats, birds, amphibians, fish and insects all take advantage of this abundant food source. Called "manna", for the enormous biomass thus provided.

Nowadays, we hardly see the spectacular spring swarms of mayflies anymore. Victims of pesticides, of the loss of their habitats, of their attraction for artificial lights, they are in clear regression. What if the manna of the wetlands disappeared?

The damselflies, an aerial ballet above the pond

From spring to autumn, the damselflies come to brighten up the pond, twirling between the rushes, typhas and sedges. Experienced pilots, they chase their prey in full flight, putting in place astonishing amorous parades. Then they disappear at the beginning of the winter, leaving their aquatic larvae to survive the bad season.

An international reputation

The Damselflies stand out among the insects of wetlands by their colorful hues, metallic blue, fire red, straw yellow, bright turquoise ... Their four finely ribbed translucent wings are often shaded with the colors of the body.

At rest, they fold like a book along their fine and graceful body. Characteristic differentiating them from their cousins the dragonflies, keeping them well spread out, in horizontal position.

Damselflies, also called Agrionians, Zygopterans, are classified among the Odonates, hundreds of species exist around the world, all leading a half aquatic, half aerial life, the young growing underwater, as larvae.

A half aquatic, half aerial life

At their birth, the small larvae of Odonata have an entirely aquatic life. They must therefore breathe under water. In damselflies, three gill lamellae of variable shape can be observed at the end of their abdomen, depending on the species. Folds near the rectum also play a role in gas exchanges.

After several successive moults the larvae will leave the aquatic environment and will have to adapt to an air breathing. A network of fine tracheae runs through the body of the damselflies, bringing the air as close as possible to the cells.

Fearsome predators

Damselflies, both larvae and adults, have effective and deadly hunting techniques. The larvae, brown to gray, go unnoticed on the muddy bottom. Especially since they do not move. They wait. Eyes, antennas, sensitive bristles, on the alert. If a prey passes at a distance that seems to maintain a certain but illusory security, it deploys a lip mask. At great speed. And catches small insect larvae, crustaceans, worms... The victim is crushed, swallowed. The mask then folds under the head, "masking" in certain species a part of their face. To leave towards a new hunting territory, the larva moves on its six legs and undulates with its gill lamellae, which act as fins.

Hunting pilots

Adult damselflies have nothing to envy to their young. They hunt in flight. Mosquitoes, butterflies, mayflies, flies, all small insects are potential targets. Their big round eyes, well detached, spot any movement. Fast, with their four wings, they melt on their preys, capture them with their front legs, bring them to their mouth, crush them before swallowing them. During the summer season, they fly all over the world, regulating many human pests.

Males and females, aerial meetings

In spring, real ballets begin above ponds, puddles and streams. The male Agrions locate their territory, watch it, invite a pretty partner. They delicately seize her by the neck, from the end of their abdomen. The female thus maintained will bend to bring the end of her own abdomen towards the penis of the male. This one being located at the beginning of the abdomen, it follows a figure of speech evoking a heart. And the eggs are ready to be fertilized.

A laying under close supervision

The fertilized damselfly decides to lay eggs. Under the close supervision of her partner. Depending on the species, he will hold her by the neck during the whole operation. Or he will stay close to her to ensure a close protection. The laying, dozens of eggs, will be made inside the plant tissues, under the leaves of water lilies, along the stems of rushes, cattails...

The first larva will leave its plant hole, and will quickly take the long and fine aspect of the larvae of Zygoptera. Several moults will follow one another during several months, even several years according to the species, to reach the size of transformation into winged adult. The larva then climbs on the plants, tears its old envelope, deploys and dries its wings and its new body before taking its flight.