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This article includes some of the most interesting types of fishes to breed in my opinion.
Different fishes have evolved different ways of caring for their offspring.
Sometimes it's the male, sometimes the female and sometimes both parents
that take part in the parental care.
Sometimes even the offspring of other individals of the same species,
or the offspring of parasitic (or opportunistic) species, can also be taken care of by surrogate parents.
Side note: The embedded links inside this article point to the corresponding webpages at Wikipedia,
except for any link that states the name of a different website.
Examples of a few different ways of caring for their offspring:
Ex 1. Bubble nest builders, also known as aphrophils:
The eggs and newly hatched fry are usually guarded and tended to in the nest by only the male in most bubble nest builders.
(Some snakeheads can also have the female participate.) Examples of common bubble nest builders in the aquarium hobby:
Ex 2. Mouthbrooder with oral incubation (buccal incubation):
I am mainly refering to ovophile mouthbrooding, which means having an affinity for brooding eggs in the mouth for extended periods of time.
This behaviour is also called ovophilous mouthbrooding or immediate mouthbrooding.
All the eggs from a spawn are immediately stored in the mouth of just one parent during the spawning.
The act of mouthbrooding with oral incubation is is also called "holding".
It refers to holding incubating eggs, wigglers (fry larvae) or free swimming fry in the mouth.
After the fry hatch the parent continues the mouthbrooding behaviour.
The parent holds the newly emerged wigglers (fry larvae). Later in the development the fry become free swimming.
Sometimes the fry get to temporarily leave the mouth of the parent, but are soon taken back inside the mouth again.
The free swimming fry that leave the mouth temporarily have instincts to return to the mouth.
They also learn to rapidly return whenever the parent calls them back.
The incubation usually continues until the young can start to take care of themselves and are let go (or forced to leave).
There are some exceptions, but usually a mothbrooding parent does not eat, or eat very little, while incubating offspring.
The parent will usually gradually loose weight during the incubation period, until the fry are let go.
After a completed incubation, it is usually recommended to let the parent eat and recover in a protected environment for some time,
until the fish is back to full health again, before letting it breed again with a mate.
When only the female is doing the mouthbrooding it is called maternal mouthbrooding.
When only the male is doing the mouthbrooding it is called paternal mouthbrooding.
When both the male and the female share responsibility and take turns doing the mouthbrooding
it is called biparental mouthbrooding. Biparental mouthbrooding with oral incubation is very rare.
There are also some fishes that are larvophile mouthbrooders. They lay eggs in the open or in a cave, but don't incubate
the eggs in the mouth. Instead they wait until after the eggs hatch and only then incubate
wigglers (fry larvae), and later free swimming fry, in the mouth.
Many species temporarily use their mouths to relocate their offspring (eggs, wigglers or free swimming fry)
usually a few offspring at at time, to a new location, or to collect some (that has fallen or strayed) and spit them back.
Many species tend to eggs, wigglers and free swiming fry using their mouths.
Some people, including some scientists, also call similar types of behaviours mouthbrooding,
but I and many other aquarists prefer not to do so.
I usually call it tending to the offspring using their mouths.
It is not wrong to call such behaviour mouthbrooding, as long as you don't call it oral incubation (if it is not),
but it is too confusing and misleading, since most aquarists think mouthbrooding and oral incubation is the same thing.
I (and probably most aquarists) prefer to separate the behaviours into different categories depending on
the degree of time the offspring stays in the mouth, and depending on if the whole brood initially will be put in the mouth at the same time,
or if the mouth is only remporarily used.
If the mouth is only used temporarily, similar to an apendage or a tool, then I personally (and probably most aquarists)
prefer to avoid calling it mouthbrooding, even if some scientists or other people might still call it mouthbrooding.
On the other hand, if the mouth is used similar to a pouch for long term oral incubation (storage during development),
then I (and probably most aquarists) all agree to call it mouthbrooding.
Examples of ovophile mouthbrooders in the aquarum trade:
- Males of: Silver arowana
(Osteoglossum bicirrhosum)
- Females of: Australian arowana
(Scleropages jardinii)
- Females of many different species of cichlids in Africa. It is especially common among many of the
popular cichlids in the aquarium hobby such as
Aulonocara, Cyphotilapia, Haplochromis, Labidochromis, Maylandia, Pseudotropheus, Tropheus etc.
Most of the popular ovophile mouthbrooding cichlids originate from the lakes in
Great Rift Valley in East Africa, such as
Lake Malawi,
Lake Tanganyka and
Lake Victoria.
There are also some ovophile maternal mouthbrooding cichlids in rivers and other lakes in Africa.
The males of ovophile maternal mouthbrooding cichlids often have patterns on their anal fins, and/or caudal fin, that resemble eggs.
These are called eggspots and the male presents them like decoys on the location where the real eggs are laid by the female.
The female, usually, try to pick up the eggspots along with the real eggs.
While the female picks up real eggs and tries to pick upp the eggspots, the male releases milt to fertilize the real eggs.
- There are only a few cichlids from South America that are maternal ovophile moutbrooders.
The three most well known species also happen to practice polygamy,
where a dominant male usually breeds with several females in a harem:
- A pair-bonding (monogamous) biparental ovophile mouthbrooding cichlid from Lake Tanganyika:
Tanganyika Clown (Eretmodus cyanostictus)
- A pair-bonding (monogamous) biparental ovophile mouthbrooding cichlid from West Africa:
Benitochromis nigrodorsalis
Synonym used prior to 2001: Chromidotilapia finley "Moliwe"
Most (but not all) species of Benitochromis show very similar mouthbrooding behaviour.
- Males of: Mouthbrooding fightingfish (Betta pugnax)
- Males of: Banggai cardinalfish
(Pterapogon kauderni)
Examples of larvophile mouthbrooders in the aquarum trade:
Larvophile mouthbrooders don't incubate the eggs in the mouth, but they do incubate
wigglers (fry larvae), and later free swimming fry, in the mouth.
- A pair-bonding (monogamous) biparental larvophile mouthbrooding cichlid from West Africa:
Bates cichlid Benitochromis batesii
This is the only species of Benitochromis that is known to be a larvophile mouthbrooder,
instead of an ovophile mouthbrooder, like the other species of Benitochromis.
- Most species of Gymnogeophagus are larvophile mouthbrooders.
(Except Gymnogeophagus rhabdotus, which is not.)
Ex 3. To lay sticky eggs in a single location openly.
Both parents usually guard and clean the eggs. The eggs stick almost like glue to whatever they were laid on,
usually plants, leaves, stones or wood in the wild. In aquariums the eggs can often also be laid on flowerpots,
glass walls, algae magnets, spawning cones or filters etc. After the wigglers (fry larvae) have hatched,
the parents continue to care for them as they develop into free swimming fry. The parental care usually continues
until the fry become juveniles (or close to juveniles) and can take care of themselves.
In freshwater this is mainly done by many species of cichlids.
The parents may use their mouths to tend the eggs, wigglers and free swimming fry. They may clean the eggs and remove dead eggs.
They may also pick up one or a few newly hatched wigglers at a time with their mouths and spit them back among
the eggs, or they may move the wigglers to a new location, often a small pit dug by the parents. The parents may
also collect straggling fry and spit them back into the main brood, but the parents do not usually incubate
the eggs in the mouth, like oral incubators do. Although it is not oral incubation, the use of
the mouth to tend to the brood is often refered to as a form of mouthbrooding by biologists,
however (unlike biologists) most aquarists instead reserve the term mouthbrooding only for the
oral incubators.
When the fry get free swimming they will usually follow one or both parents. The parents herd the fry around.
The parents often use interesting body language and behaviors during this time.
Usually the parents also change to a different tone of color during the herding of the fry, so the fry can
more easily recognice their parents and their signals.
A few especially adapted cichlids (Symphysodon sp. and Uaru sp.)
also nurse their young by providing them with their parental slimecoat as food for the fry to eat and grow faster.
Ex 4. To lay sticky eggs above the water!
The male splashing tetra
(Copella arnoldi)
splashes water on the eggs that have been laid and fertilized above the water
under a leaf, root, aquarium glass cover etc. The male does this until the eggs
hatch and the fry fall down and swim away.
Ex 5. To lay the eggs hidden inside caves, shells etc.
This is done by many (but not all)
plecos and also many (but not all)
dwarf cichlids.
The different species of plecos that are cavespawners only have the male guarding their offspring, until the fry have
consumed their yolk sacs and leave the cave. This can take weeks of guard duty, so the fry are
usually fairly large by the point they finally leave the cave and start foraging for food.
Many dwarf cichlids develop pair bonds, but there are also species of dwarf cichlid males that sometimes have a harem with females.
Polygamy is common among Apistogramma.
Then it's usually the females that closely guard the offspring while the male defends a larger terriotory.
In some species both parents help to guard the eggs and fry, until they can take care of themselves.
Sometimes one or both parents herd the swarm of freeswimming fry or even juveniles,
long after the fry have initially left (or been moved from) the original spawning cave etc.
Some species of cichlids live in species communities.
Relatives of different ages, from many different broods, are mixed in the same colony.
The eggs and wigglers (fry larvae) are normally closely cared for by their parents, but later when the fry become free swimming,
eventually the whole community works together to raise the fry.
This strategy is generally not common, but an exeption is in Lake Tanganyika, where it is common.
Neolamprologus and
Lamprologus often live in mixed aged communities.
Ex 6. To act as a parasite, or a symbiont:
For example cuckoo catfish (Synodontis multipunctatus and
Synodontis grandiops) that can use mouthbrooding cichlids to guard their
catfish eggs and catfish fry, while the eggs and fry of the cichlids get eaten by the catfish fry.
Bitterlings (Rhodeus)
are known for laying their eggs in a living freshwater mussels. The offspring is well protected in the mussel,
until they get freeswimming and leave the mussel.
In the wild, the different species of
clownfish have symbiotic relationships with a few specific
species of sea anemones and they have adapted to eachother. A pair of clownfish spawn very close
to the base of the anemone, where the eggs get partial protection while they are being tended
to by the pair of clownfish.
Ex 7. For males to use a belly pouch for paternal incubation of the eggs:
Seahorses and some species of
pipefish use this internal-brooding method.
A female will deposit a cluster of eggs into the abdominal pouch of the male.
The male will carry the eggs in the pouch.
The eggs hatch and the males will give birth to fry by ejecting free swimming fry from the pouch.
Ex 8. For males to carry the eggs on a brood patch, externally on their tail:
Seadragons
(Phycodurus and
Phyllopteryx) and some species of
pipefish use this method.
The hatchlings will swim away from the brood patch when they hatch.
Ex 9. To use internal fertilization together with complete maternal internal incubation:
This includes any species where the female protects her fertilized eggs in the oviduct in her body,
until the eggs begin hatching (or sometimes longer) inside her. Then she gives birth to free swimming fry or pups,
although in some cases the eggs immediately hatch into free swimming fry during the birthing procedure.
- Many (but not all) livebearers.
Please note that this page on wikipedia also includes other types of
livebearers such as mouthbrooders etc.
Usually when aquarists generally talk about livebearers in the aquarium hobby,
the aquarists usually only refer to the livebearing toothcarps of the family
Poeciliidae, such as:
Guppy,
molly,
platy,
swordtails,
mosquitofish and
Endler's livebearer etc.
- Livebearing toothcarps of the family
Anablepidae such as
four-eyed fish.
- Livebearing halfbeaks. This includes most (but not all) members of the family
viviparous halfbeaks
Zenarchopteridae.
Please note that the common family name viviparous halfbeaks for this family is slightly misleading,
since not all members are viviparous.
Some are instead oviparous species, with incomplete incubation, that lay eggs.
- Most freshwater stingrays
from South America are known to give live birth to pups, while the reproduction ways of some species are still unknown.
Please note than not all species of rays (in marine, brackish or freshwater environments) from other locations reproduce this way.
There are also other rays that lay eggs.
- Some species of sharks are known to give live birth to pups.
The shark pups are sometimes also called cubs.
Please note than not all species of sharks reproduce this way.
There are also other sharks that lay eggs.
Ex 10. Ricefishes:
Ricefishes are a diverse group of fishes. There are several different strategies among different species of
ricefish.
Some ricefishes use internal fertilization and let the embryos partially develop,
but lay the eggs before they hatch, so they do not give live birth.
Some ricefishes use external fertilization and the females carry the eggs outside their bodies in clusters,
hanging from the genital pore, close to, or in between, the pelvic fins.
Some of those species deposit the eggs during or soon after the spawning, while others carry the eggs longer.
Some only seem to carry the eggs until they find a suitable place to deposit them,
while others perhaps carry the eggs until they start to develop visible larvae inside the eggs,
or maybe they only deposit the eggs when they are ready to spawn again and push out a new brood clutch of eggs?
I don't know, but it would make sense to prolong the time the developing eggs are protected by the female,
since it is usually more dangerous for the eggs during the period after being deposited without protection.
However, only a few pelvic-brooding species actually brood the eggs all the way until they hatch.
The spawning and fertilized by the male ricefishes usually occurs during the morning.
In most of the species common in the hobby, the females usually deposits the eggs among plants, or other media, during the same day.
In ideal conditions with plenty of food and great water quality, a female may be ready to spawn again the next morning,
or a few mornings later, depending on the species and temperature etc.
External links about breeding behavior:
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