Ornamental Aquarium Fish

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Ornamental aquarium fish hobby is very relaxing and enjoyable and is an educational experience. However as these aquatic pets are delicate when compared to mammalian pets and live in a very small and delicate environment, the ornamental aquarium hobbyist must know at least the basics of fishkeeping to be successful.

This endeavour, ‘Ornamental Aquarium Fish’ is to educate the beginner as well as provide useful information for the experienced hobbyist. In ‘Ornamental Aquarium Fish’ continuous efforts are being made to give the user/fishkeeper complete and frequently updated information on ornamental aquarium pets.

The visitor can get exhaustive information on setting up ornamental aquarium fish bowls, ponds, tanks and reefs. There are many articles on procuring, installing and maintaining ornamental aquarium equipment and accessories. In Ornamental Aquarium Fish you can find information on the basically different environmental requirements in freshwater and marine (saltwater) tanks.

As tropical ornamental aquarium fish tanks require special care, pertinent information is being given for the beginner as well as experienced hobbyist. In the confined, delicate environment, the ornamental fish are prone to diseases and environmental stress. These aspects of fishkeeping are discussed and explained here.

An ornamental aquarium enthusiast is overwhelmed by the staggering numbers of aquatic fish species available. More than two thousand species animal specimens making up the ornamental pets. Majority of the aquatic pets are of freshwater origin and are raised in farms.

However a few freshwater varieties are still sourced by the traders from wild collections. Most of the marine ornamental aquarium varieties (over 90%) are collected from natural habitats. Aquatic pets include vertebrates such as fish, reptiles, amphibians and also invertebrates such as shrimps, crabs, snails and live corals and live rock.

Countries making up the European Union are the largest market for aquatic pets and United States is the largest importer of ornamental pets in the world. It is estimated that the aquarium industry is worth more than 1000 million US dollars.

Ornamental freshwater aquarium

Aquatic pets have either freshwater or marine origins. Some species tolerate brackish (low saline) water. Freshwater ornamental species may have tropical or coldwater origins. Tropical specimens must be kept in a warm heated ornamental aquarium.

For the fishkeeper, a typical tropical tank has heating arrangements and plantations. Cichlids, bettas, tetras, angelfish, loaches, guppies, barbs, mollies, platys and swordtails can be kept in a tropical aquarium.

Coldwater species like goldfish, koi and White Cloud Mountain minnows, can withstand room temperature in temperate zones and are quite comfortable at around 60°F (15°C). Ornamental koi can even be kept in an outdoor pond and can stand temperatures down to 10°C.

Marine (saltwater) aquarium

Most of the saltwater species of ornamental fish are of tropical origins. The marine ornamental aquarium may hold, fish only or in combination with live rock. There are tanks dedicated to reef environment.

To have a successful marine aquarium tank, stringent water quality monitoring is a must. Reef tanks are primarily designed to house corals and other invertebrates. Acclimation is very important for saltwater species. The salinity at the stores and in the tank in the home may vary widely. The ornamental fish must be slowly acclimatized to the aquarium tank.

Fish bowls

Fish bowls are available in many sizes and fancy shapes. Though small specimens like feeder guppies can do well in a small half gallon bowl, as an act of kindness to the pets, I recommend a two gallon bowl for keeping your aquatic pet. Please note that the governments of two Italian cities, Monza and Rome have banned the use of round goldfish bowls.

If you want to keep goldfish bowls check up with your local lawmakers. Do not keep goldfish in a bowl. It is too small a place for a fast growing variety. Ornamental aquarium guppies, White Cloud Mountain Minnows, bettas, barbs, mollies, platys and ghost shrimps are ideal pets for keeping in bowls.

Fish tank aquariums

Ornamental pet tanks are usually made from glass or high-strength acrylic plastic. An acrylic tank is crack-resistant, light in weight, stronger than glass and available in different shapes.

They are manufactured in various sizes and shapes. Sizes may vary from a small 80 liter tank to huge public aquarium. Though the general shape is cuboid, ornamental aquarium tanks with hexagonal shape, L-shape, bow-front and circular shape are also available.

Ornamental aquarium equipment

The basic requirements for fishkeeping, apart from the tank, are a filtration system, an artificial lighting system, and a heater or chiller. Usually a stand is required for placing the ornamental tank. Containers for holding aged water for water exchange are also needed.

Appropriate gravel is required, taking the size of the pet and habits of the pets into consideration. A standby power generator may also be required. A kit to analyze aquarium water quality is a must.

Ornamental aquarium fish food

Prepared foods in the form of flakes, pellets or tablets are used to feed the pets. Aquarium food blocks are available, which release the feed slowly over considerable time. Ready made medicated feed is given when the pets are diseased. Frozen food, dried food and live food are also available and are given to enhance the color of the specimen as well as to take care of protein requirements.

Aquarium fish diseases

Aquatic medicine is fast emerging as an important specialty within the practice of veterinary medicine. The ornamental aquatic pets are becoming highly prone to diseases. In wild specimens the genetic diversity is maintained and enhanced by natural cross breeding. However the habitats have become highly polluted and the wild ornamental aquarium specimens are already under stress and easily contract infections and diseases.

Farm raised ornamental aquatic pets may be hygienically maintained by the farmer/trader. But they are always selectively bred or inbred to develop new strains, which makes them lose their natural resistance and immunity to diseases. They easily contract diseases and develop genetic deformities.
For further information on the types of aquatic pet diseases and their remedies read the topic ‘common fish diseases‘.

European perch (Perca fluviatilis)

Ornamental aquarium fish   >   West African lungfish   >   European perch – Perca fluviatilis.

The European perch (Perca fluviatilis) belongs to the Family Percidae (darters, perches) in the order Perciformes (Perch-like) and in class Actinopterygii (ray-finned fishes).

The European perch is a predatory fish and lives in brackish and freshwater waters. It is commonly known as European perch, redfin perch, Eurasian perch, Perche européenne (French), Zockkrätzer (German) and Обыкновенный окунь (Russian).

There are several synonyms of Perca fluviatilis Linnaeus, 1758, and some of them are, Perca vulgaris Schaeffer, 1761, Perca fluviatilis maculata Smitt, 1893, Perca vulgaris aurata Fitzinger, 1832 and Perca fluviatilis gracilis Pokrovsky, 1951.

The European perch is widely distributed in Europe (excluding the Iberian peninsula) and north and west Asia. It is a popular quarry for anglers and has been introduced into Australia, New Zealand, South Africa, Spain, Portugal, Italy, Cyprus, Morocco and China. Adverse ecological impact on the native fish populations has been reported. Being a hardy species, it is raised both in outdoor and indoor aquaria.

European perch - Perca fluviatilis
European perch – Perca fluviatilis
European perch aquarium
European perch aquarium
European perch facts
European perch facts

Appearance, physical description and identification

The body of the European perch is deep and laterally compressed. The body shape is fusiform (spindle-shaped). The mouth is in a terminal position on the snout. The scales are rough and ctenoid. The lateral line is uninterrupted and has 56 to 77 scales.

The eyes are large, adapted for murky waters. The operculum has a spine on its margin. There are two dorsal fins which are clearly separated. The first dorsal fin is higher than the second dorsal fin. The first dorsal fin has a total of 14 -20 spines.

The second dorsal fin has only soft rays. The caudal fin is emarginate. The common length of the perch is 25.0 cm and the maximum recorded total length (TL) is 60 cm. The maximum published weight is 4800 grams. These perch species may live up to 22 years in wild conditions.


The body color is olive green to gray on the dorsal side and fades into greenish silvery sides. The belly is whitish. On the flank of the fish, there are 5 to 8 bold transverse black bands. The pelvic, anal and caudal fins are colored orange red.

The pectoral fins are pale yellow. The first dorsal fin is gray and there is a dark blotch on its posterior part. The second dorsal fin is greenish yellow.

Meristics and morphometrics of blue ring angelfish

Lateral line: uninterrupted;
Scales on lateral line: 56 – 77
Scale rows above lateral line: 7 – 10
Scale rows below lateral line 12 – 21
Total gill rakers: 14 – 20;
Total preanal vertebrae: 39 – 42
Dorsal fin: 2 (clearly separated); total dorsal spines: 14 -20; total dorsal soft rays: 13 – 16
Adipose fin: absent
Caudal fin: emarginate
Anal fin: 1; anal spines: 2; anal soft rays: 7 – 10
Pectoral fin: spines: nil; soft rays: 11 – 17
Pelvic fins: spines: 1; soft rays: 5 – 6

European perch habitat and ecosystem

The habitat of these perch species include, brackish water estuaries, lagoons, brackish seas, freshwater rivers, streams, lakes and ponds. It is an anadromous fish, migrating up streams and rivers for spawning.

The European perch is usually bottom living and its preferred depth range is from 3 – 4 meters. It prefers still or slow-flowing waters. The European perch is usually found in sheltered areas like dead wood, submerged trees, aquatic vegetation and rocks.

It is also caught from open areas. It does well in cooler waters and its preferred temperature range is around 15°C and is comfortable in the range 10°C – 22°C. The ideal pH range is 7.0 to 7.5. The preferred range of general hardness of water (dH) is 8 – 12.

Origin, geographical range and distribution

The European perch is a native fish of most of the countries in Europe, except for Iberian peninsula (Spain and Portugal) and Italy, where it has been introduced.

In west Asia it is native of Afghanistan, Iran, Turkey, Uzbekistan, Kazakhstan, Armenia, Azerbaijan and Georgia. The European perch has been introduced into Cyprus in this region. In the northern Asia, European perch is native fish of Russia and Mongolia. It has been introduced in China.

In Africa, it has been introduced into South Africa and Morocco. It was introduced into Australia in 1860s and later into New Zealand. New South Wales state has listed these fish as a Class 1 noxious species in December 2010 due to the devastating effects on the native fish populations.

European perch behavior and adaptations

These fish species are well adapted for their predatory life. Anything appearing as potential prey is attacked and taken into mouth. This nature makes them ideal fish for anglers.

In an aquarium, they will attack any smaller moving animal. So, they must be kept along with bigger fish in a community aquarium. After a year or two, you may have to upgrade to a bigger aquarium as they can grow to 12″ size and more.

The adults spend a solitary existence, while the larvae and young juveniles of perch tend to live in groups. These perch species have slower growth rate when compared with other perch species.

Growth is at its maximum after spring and during summer, when the temperatures go up to 23°C. At the end of autumn and during winter, the growth is minimal and in some cases the growth may cease.

Diet and feeding habits

The European perch is a predatory fish and its diet includes smaller fish, crustaceans, worms, molluscs, insect larvae and other macrofauna. The European perch feeds mostly during sunrise and sunset.

In larval and small juvenile stage they first feed on algae and zooplankton (rotifers, cladocerans and copepods). Cannibalism is an important characteristic of juveniles and fingerlings of the European perch.

In aquarium, European perch can be trained to feed on live worms and feeder fish like inexpensive guppies, mosquito fish, platies and goldfish. It may also feed on fish meat and clam meat. Smaller European perch can be trained to accept formulated flake and pellet feeds.

European perch reproduction and development

The male fish is slightly smaller than the female and it is difficult to differentiate the sexes. The European perch breed once in year when there is increase in temperature and photoperiod. However, to mature, perch need at least 160 days of cold conditions wherein the temperature is below 8°C.

These species spawn in shallow waters and release their eggs on substrates like plants and dead wood. The eggs are held together by a long ribbon-like gelatinous matter.

The European perch fecundity under natural conditions varies widely between 15,000 to 300,000 eggs. The development of perch eggs and their hatching depends upon the water temperature. At temperature around 15°C, the eggs may hatch in about seven days.

The hatchlings feed on phyto and zooplankton. Breeding in captivity is a large thriving industry with modern inputs like, controlling light duration and intensity for maturation, induced breeding, egg incubation and hatcheries and mesocosm culture systems.

Conservation status and concerns

IUCN Red List status has evaluated and listed these European perch species as of ‘Least Concern’ (LC). These fish are not considered endangered and there is no restriction on catching, collecting and breeding them for human use including aquarium trade in their native countries.

There are restrictions prohibiting European perch release in non-native countries. CITES status is ‘Not Evaluated’. European perch is considered as potential pest in non-native areas and otherwise it is considered “Harmless” to humans.


1.Image source: https://en.wikipedia.org/wiki/File:Perca_fluviatilis2.jpg
Image author: Citron | License: CC BY-SA 3.0
2.Image source: https://commons.wikimedia.org/wiki/File:PercheCommune.jpg
Image author: Dgp.martin | License: CC BY 3.0
3.Image source: https://commons.wikimedia.org/wiki/File:Perca_fluviatilis_Prague_Vltava_2.jpg
Image author: Karelj | License: public domain
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