Animal-World > Freshwater Fish > Killifishes | Tooth Carps | Pupfishes | Topminnows

KillifishesTooth Carp ~ Pupfish ~ Topminnows

Family: AplocheilidaeGolden Wonder Killifish
Aplocheilus lineatusPhoto © Animal-World

     The Killifishes are very diverse and extraordinary fish, highly favored by dedicated aquarists!

     Killifish are intriguing and quite beautiful. They come from many diverse habitats and range from hardy to extremely difficult to keep. Many species can be demanding and have quite specific needs. As each type will have its own set of requirements they are often kept in species tanks. In general most of these fish are best kept by very dedicated aquarists who are prepared to research the individual species and provide them with top quality water conditions and top quality food. When their needs are met many can readily be kept in captivity and most will spawn.

     The order of Cyprinodontiformes, with over 800 species and currently classified into 10 families, are commonly known as Killifish. This is a very widespread and diverse group of fish, primarily Killifish but also including such species as Pupfish and Topminnows. They are found in tropical and subtropical regions on all continents except Australia. They are also absent from Antarctica and northern Europe. Killifish inhabit and have adapted to a wide variety of environments. They live in both moving and still waters. Mostly they are freshwater fish, however there are a few species that are brackish and some even saltwater.

For more Information on keeping freshwater fish see:
Guide to a Happy, Healthy Freshwater Aquarium

Killifishes | Tooth Carps | Pupfishes | Topminnows: Click on the small images below
for more information about each one.

Killifishes
Banded Lampeye Killifish	Blue Panchax Killifish
Aplocheilichthys spilauchen	Aplocheilus panchax
Delta Killifish	Desert Pupfish
Aphyosemion deltaense	Cyprinodon macularius
Japanese Rice Fish - Medaka	Lampeye Killifish | African lampeyes
Oryzias latipes	Aplocheilichthys kingii
Striped Panchax Killifish	Variable Lampeye Killifish
Aplocheilus lineatus	Procatopus similis

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Introduction:

     An intriguing fact about Killifish,... some species have a life span that only lasts as long as the mud puddle they live in!

     One species that basically lives in mud puddles, will hatch and then mature in just 3 weeks. They will then lay their eggs and push them into the mud just in time for the mud puddle to dry up and eliminate the parents. But when the rains come and refill the mud puddle, the eggs hatch and the cycle starts all over again!

Description:      Each species of Killifish has its own variety of colors and patternings, and many are extremely attractive. Males are the most brightly colored with the females being duller. Most all of the Killifish have heads flattened on the top. The mouth is either at the tip or in many specimens is underslung, typical of surface swimming fish. They have long pointed teeth that are usually curved. They have no barbels and almost all species have round scales. They have no lateral line but most have lateral line organs chiefly on the head.
     Though the body shape and finage varies by species, the dorsal fin is set towards the back half of the body. Also most males have larger dorsal and anal fins than females. Many of the Killifish have slender, almost pike-shaped bodies and are excellent swimmers. Then there are others with short rounded fins on a more cylinder shaped body, and still others that are deeper bodied specimens with long broad well-developed fins.
     Killifish are small fish with most species being between 2 to 4 inches (5 - 10 cm). There are just a few species that go beyond these sizes. On the smaller side there are some dwarf Killifish. The Dwarf Medaka Oryzias minutillus and the Hummingbird Lampeye   Poropanchax myersi are both less than one inch (2 cm). On the other extreme is the largest of the Killifish, Orestias Orestias cuvieri, which can reach up to 10 1/2 inches (27 cm).

Care and feeding:      As each type of Killifish will have its own set of requirements, these fish are most often are kept in individual species tanks. In general most of these fish are kept by very dedicated aquarists who are prepared to research the individual species and provide the top quality water conditions and foods it needs. When the needs of these fish are met they can readily be kept in captivity and many will spawn.
     The diet of Killifish varies by species. Most are carnivores eating aquatic crustaceans, insect larvae and worms. Having a great appetite for insects and insect larvae, Killifish in some areas have been found to be important for mosquito control. There are some species that are predatory stalking other fish, and some that are omnivores so will include algae in their diet. In the Aquarium they will eat live foods including insects, mosquito larvae, water fleas, and various small worms. They will also eat freeze-dried live food and dry food.
     The majority of the Killifish are small fish, and though most are not found in shallow water many of the species kept by aquarists are. Consequently an aquarium for them does not need to be particularly large or deep. Depending on the species and the number of fish you are keeping, the tank size can range from 5 gallons and up.
     Be sure to research each species for their own special considerations and maintenance requirements. Then provide an environment that is similar to their natural habitat. Most species are found in water that is soft and slightly acid, but often Killifish can slowly be acclimated to other water conditions. The natural distribution of seasonal species, those that live in small pools or flood plains, can be very specific and can have very extreme conditions. For example the puddles of some species can have an extremely high salt concentration, up to 20%, which makes their environment six times more salty than seawater.
     As the males are usually aggressive, the aquarium decor needs to provide plenty of hiding spaces among roots and rocks. The aquarium can be planted and some floating plants will provide a more dimly lit tank. Use a fine gravel for the bottom substrate that is dark in color.
     Though they are a few species that will temporarily form schools, most often these fish swim alone or in loose groupings. Behavior is different for each individual as well as each species, but males are often quite quarrelsome. If keeping more than one in a small tank, it is best to keep either a pair or one male with two females. In larger aquariums most species can be kept as a group as long as there are more than three males.

Breeding:      Most species of Killifish are sexually dimorphic. Males are much more colorful than females and will have larger dorsal and anal fins.
     Having adapted to life in very diverse habitats, the Killifishes are divided into two groups based on different methods of reproduction that they employ. The first group of Killifish are those that are bottom spawners, pushing or burying their eggs in the substrate. The second group are the 'egg-hangers', those that usually spawn on plants to which the eggs then adhere. Killifish are either of the short-lived 'seasonal' or annual species or they are of the longer-lived non-annual species.

• Seasonal or 'Annual' species:
       Most surprisingly, some species that spawn on the bottom live a very short 'seasonal' life in mud puddles or flood plains. When the mud puddles dry up so do the fish, except for the eggs they left behind buried in the mud. When the rains come again, the next generation of fish is born to repeat this short life cycle.
     Because the entire life span of these fish is no more than 8 months they are considered seasonal or annual fish. In the aquarium they also have a short life span, usually only up to about 1 1/2 years.
• Non seasonal species:
       These are species that live where there is always water. Most will spawn on plants though there are a few species that spawn on the bottom. They produce eggs that will adhere to the plants. These fish are longer living in the wild, usually 3 to 4 years
• . Many of these have been kept for 5 or so years in the aquarium.

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