List of brackishwater and Introduced fish of Sri Lanka

Class: Actinopterygii - Ray-finned fishes

Since Sri Lanka was ruled by Portuguese, Dutch, and British, they began introducing a number of exotic species including mammals, plant, birds and fish. The introduction of the fish has led to serious ecological damage, because they always damage the internal diversity and extinction of endemic fauna as well. Most of these exotic species brought for commercial purposes, such as seafood and aquarium fish. But releasing them to natural ecosystems will result many harms. Exotic fish in Sri Lanka is become now serious, due to invasiveness.

There are 8 known marine and brackish water fish that enter freshwater ecosystems in and around Sri Lanka.

Family: Clupeidae - Clupeids

Many members of the family have a body protected with shiny cycloid scales, a single dorsal fin, with a fusiform body built for quick evasive swimming and pursuit of prey composed of small planktonic animals.

Family: Megalopidae - Tarpons

They are able to survive in brackish water, waters of varying pH, and habitats with low dissolved O
2 content due to their swim bladders, which they use primarily to breathe. They are also able to rise to the surface and take gulps of air, which gives them a short burst of energy.

Family: Gobiidae - Gobies

Generally, they are benthic, or bottom-dwellers. Although few are important as food for humans, they are of great significance as prey species for commercially important fish such as cod, haddock, sea bass, and flatfish. Several gobies are also of interest as aquarium fish.

Family: Toxotidae - Archerfishes

Known for their habit of preying on land-based insects and other small animals by shooting them down with water droplets from their specialized mouths.

Family: Zenarchopteridae - Viviparous halfbeaks

They exhibit strong sexual dimorphism, practicing internal fertilisation, and in some cases ovoviviparous or viviparous (the family also includes oviparous species).

Family: Hemiramphidae - Halfbeaks

They are commonly called 'Half-beaks, for their distinctive jaws, in which the lower jaws are significantly longer than the upper jaws.

Family: Syngnathidae - Pipefish and seahorses

The name is derived from Greek, syn, meaning "fused" or "together", and gnathus, meaning "jaws". This fused jaw trait is something the entire family has in common.

An introduced, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its native distributional range, which has arrived there by human activity, either deliberate or accidental. Non-native species can have various effects on the local ecosystem. Introduced species that become established and spread beyond the place of introduction are called invasive species. Some have a negative effect on a local ecosystem. Some introduced species may have no negative effect or only minor impact. Some species have been introduced intentionally to combat pests.

There are 24 introduced fish species which inhabit all freshwater, brackish water and marine waters.

Family: Cyprinidae - Carps and allies

Cyprinids are stomachless fish with toothless jaws. Even so, food can be effectively chewed by the gill rakers of the specialized last gill bow.

Family: Salmonidae

All salmonids spawn in fresh water, but in many cases, the fish spend most of their lives at sea, returning to the rivers only to reproduce. This lifecycle is described as anadromous. They are slender fish, with rounded scales and forked tails.

Family: Poeciliidae - Guppy and swordtails

They are extensively used for mosquito control, poeciliids can today be found in all tropical and subtropical areas of the world.

Family: Cichlidae - Cichlids

Cichlids are popular freshwater fish kept in the home aquarium. Cichlids tend to be of medium size, ovate in shape, and slightly laterally compressed, and generally similar to the North American sunfishes in morphology, behavior, and ecology.

Family: Osphronemidae - Gouramis

Many gouramis have an elongated, feeler-like ray at the front of each of their pelvic fins. Many species show parental care: some are mouthbrooders.

Family: Helostomatidae - Kissing gouramis

Single species is known. The kissing gourami is a popular aquarium fish.

Family: Loricariidae - Suckermouth fishes

These fish are noted for the bony plates covering their bodies and their suckermouths. They are popular as aquarium fish.

Family: Notopteridae - Knifefishes

Known as knifefish or featherbacks, have slender, elongated, bodies, giving them a knife-like appearance. The caudal fin is small and fused with the anal fin, which runs most of the length of the body. Where present, the dorsal fin is small and narrow, giving rise to the common name of "featherback".