Section 9: Breeding Fish
(by
theaquarian April 25, 2001)
 One
of the most interesting aspects of the aquarium hobby is breeding fish.
For me, watching fish is fun, but watching how they react and behave to
certain situations is much more exciting. Being able to breed fish and
watch their behavior as they raise their young is the one real big
advantage that freshwater fish-keeping has over saltwater fish-keeping.
There is something amazing and inexplicable about watching a male betta
continually rebuilding a next built out of bubbles, while at the same time
catching fry that mistakenly swim or fall out. Equally as interesting is
watching a female kribensis gather up her young into her mouth, just a few
at a time, and then moving them over to the cave where they will spend the
night.
Whether it's cichlids,
gourami or guppies, fish are exciting to breed. What's more, raising up
the fry provides an exciting glimpse into nature. However, not all fish
are easy to breed. And even if you can breed them, then what do you do
with the fry? Raising the fry often turns out to be much harder than
breeding the fish ever was. If you've ever wanted to breed a fish, but
were unsure how to do so, this article is for you.
Though there are many
types of fish, most of them fall into one of 6 categories: mouth
brooders, egg layers, shell dwellers, bubble-nest builders, egg scatterers,
and livebearers. This article will not cover the particulars of breeding
any one fish as even within the categories, there are wide variations in
how the fish breed. If you’d like to look at the specifics on breeding
any one type of fish, the fish index
section of the site should be of great value to you.
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| A holding female albino Eureka peacock.
Notice how the mouth looks very full. Holding females do not eat
while they are holding. |
Mouth
brooders are fish that hold their eggs in their mouth until their young
are free-swimming. This is somewhat common in cichlids; the peacock
cichlids of lake Malawi are good examples of this type of breeding.
Sexing of these fish can vary greatly. The aforementioned peacock
cichlids are easy to sex as the males are absolutely beautiful, exhibiting
bright yellows, reds and blues, while the females tend to be steel
colored. Other fish in this category can often be sexed by comparing the
dorsal fins. Males typically have dorsal fins that end in a point, while
females dorsal finds are usually rounded.
The
main advantage of mouth brooding is that the young are larger and fully
able to survive on their own when they are released. In some cases, the
parents will be used for a safe harbor after the young have been
released. In the aquarium mouth brooders can be difficult to care for.
In the wild, the holding fish will usually group together away from the
rest of the fish. Since they live in very large lakes, this is not a
problem, but in your aquarium, this becomes a bit more difficult.
You may
find that the females are beat up in your aquarium and may require
moving. However, moving the fish can cause new problems, as females will
often spit out their eggs if they become panicked.
The
remedy for this situation is a very large tank with lots of hiding
spaces. In fact, you will really need very little more to breed mouth
brooders. A ratio of 3 females to every 1 male is recommended, but even
with a 1:1 ratio, you should have to do little more than put the fish
together to get them to breed. Feeding the fish live or frozen foods may
help, as is the case with most fish, but in reality, mouth-brooders may be
the easiest of all fish other than livebearers to breed.
When
breeding mouth-brooders, it is important to keep a careful watch over your
fish. When a fish spits its fry, they fry will most likely be ravenously
consumed by the fish in the tank. To avoid this, most aquarists will
"spit" their females before they release the fry. This should be done
with great care so as to not injure the fish. In general, if there is
anyway to get the female to spit the fry without forcing her mouth open,
it would be preferred. I personally like to catch the female and put them
in either a guppy breeding trap or a similarly sized net. Most females
will soon release their fry because they are so stressed about being
caught in a small place. Though this will frighten the female, it will
only be for a short time it is certainly better than man-handling and
possibly injuring the female.
Fry from mouth brooding fish are
usually quite large, and can be removed to a fry-raising tank
immediately. As is the case with most cichlids the young will readily eat
just about anything you throw at them, so purchasing a specialized fry
food will not be necessary.
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The Similis is one of the prettiest of the
shell-dwellers. |
Shell
dwellers are really just a subset of egg-layers. I include them here as
their own category due to their very interesting behavior. Discus and
Waroo and another set of fish that deserve their own category, but I
unfortunately do not yet have any experience breeding them.
Shell
Dwellers live and breed in shells. This is most commonly achieved by the
creation of a colony as in the case of the multifasciatus and similis, but
may be in more of a pairing fashion as in the case of the black and the
gold ocellatus.
To
breed shell dwellers, it is not necessary to have shells. What the fish
is really looking for is any small tight protective area. However, it is
highly recommended that you do have shells. Any shell that has at least a
¾” opening should work fine. I’ve used sea shells, garden snail shells,
and apple snail shells. They all work great, and there doesn’t appear to
be one that is any better than any other. The only key to the shell is
that it is large enough to get into and that it doesn’t have anything dead
and decaying inside.
While
it is not necessary to have shells, it is nearly necessary to have a sand
or very fine rock substrate. Shell dwellers are great sculptors, and they
will use the sand to define their territories. Many species will also
bury unused shells so that other fish do not move into their territory.
What’s more, the females often will bury their own shells so that the
only thing visible is the actual shell opening.
Breeding shell-dwellers can usually be accomplished by placing 5 or fish
together when they are very small (ie 1” and under) Since no
shell-dweller gets over 2 inches, they are great fish to keep in small
tanks. A 10 gallon tank will usually work great for a breeding colony.
However, a 10-gallon aquarium only really allows for one male, so if you
have more than one male, you will find the other one hovering in the
corner. Still, I’ve had over 80 shell-dwellers in a 10 gallon at one time
running minimal filtration.
If you
really want to see these fish shine, try a much larger tank, say 65
gallons. It will allow for the fish to set-up multiple colonies, and
frankly, that is something to see. Very few fish are small enough that
you can see how the act in nature in your own home, but the shell-dweller
fits that bill.
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A typical bubble-nest, Day's Paradise fish is
pictured here |
Anabantids, more commonly known as gourami, paradise fish, and betta are
an amazingly interesting fish to breed. Not only are they fairly easy for
the beginner to breed, the way that they breed is extremely showy. What’s
more, the males of these fish are typically among the prettiest among
aquarium fish. They include such favorites as the betta, dwarf gourami
and pearl gourami. Sexing the fish is not difficult. They, like most
cichlids, have a dorsal fin that is a big tip-off. Females typically have
a rounded dorsal fin, whereas males have a pointed dorsal fin. Females
also tend to be much bulkier than males in the tummy section.
The
bubble-nest builders will typically breed by having the male build a nest
out of bubbles. The male will display, by extending his fins, and will
try to entice the female under the bubble-nest. The male and female fish
will embrace near the surface of the water, with the eggs being released
and falling towards the bottom of the tank. The male will catch the eggs
in his mouth and place them into the bubble nest. The process will
continue until the female is out of eggs to release, at which point the
male will become very antagonistic towards any other fish it sees. Due to
that fact, it is advisable to remove the female after breeding. The only
trick being to do so without damaging the bubble-nest. After removing the
female, leaving the male with the eggs is advisable. You will see that
the eggs will continue to fall out of the nest, and if there is no one
there to put them back, they will be lost. The nest will also need to be
rebuilt as time goes on, and the male will be there to do that when it is
necessary. In most cases, the male should be removed when the young are
fully free swimming. After the young first hatch, they will do more
falling than swimming, so leaving the male in will remain an important
thing, as he will help to place the fry back into the nest. However, once
the fry are able to swim on their own, most males will eat them, not
realizing that they are the same fry that he has been caring for.
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A personal favorite of mine, the Sparkling or
Pygmy gourami. (trichopisis pumilus) |
A
couple more thoughts about breeding bubble-nest builders. You will be
much more likely to get the fish to breed if the tank is full of plants.
Many of the bubble-nest building fish will incorporate bits of plant
matter into the nest that the build, making plants a necessity. What’s
more, having plants will often help provide microscopic food that will be
eaten by the fry as they are born. The second suggesting is that you keep
the tank shallow. I recommend filling a 10 gallon tank about half-full of
water to accomplish this. The reasons are two-fold. First, the fry
require surface air when they are young. If the tank is too deep, and
they are unable to make it to the surface quickly, they will drown.
Secondly, the air that the fry breathe from the surface needs to be
moist. If the tank is half full, and covered, a warm moist area of air
will form, that will be perfect for developing the surface-air-breathing
organ of these fish. (The labyrinth that gives this class of fish one of
its common names)
Feeding
the fry is often a very difficult task to undertake. A much finer food
must be used. The best food I can suggest is a VERY small live food. I
have tried fine “flake” foods such as OSI’s microfood with mixed results.
Powdered flake, such as tetra’s fry food is much too large for the tiny
mouths of most anabantid fry to eat. Liquid food are good, but if the
food sinks to the bottom of the tank, it will not be eaten, and it will
become possible danger to the tankdwellers.
The
anabantids are a very interesting class of fish that are as much fun for a
beginner to keep as they are for a more advanced hobbyist. They are my
personal favorite type of fish, and I always seem to be looking for a new
species to breed to see how they make their slight variations on the
generalities listed above.
Egg Scatterers (killifish, rainbowfish,
tetras, barbs)
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The Tourquoise Rainbow is one of the many
stunning rainbowfish. |
This
class of fish includes most of the fish on the planet. For this type of
breeding the most important thing is a watchful eye, as these fish almost
without fail will devour any eggs that they see. Frankly this category
should be split up at least 3 ways. Rainbowfish, Killifish, and then the
Tetras & Barbs, however, I’m not the best person to go into depth about
the differences between the 3 types, so I’m looping them together here.
Egg
scatters generally require softer water and lots of plants. They
typically will lay eggs either on a plant or on the substrate. For
rainbowfish, a “mop” is usually used. The mop consists of yarn, cotton,
not nylon, that is strung together to look like a mop. It is hung in the
tank and will almost certainly be where the fish lay their eggs if there
are no bushy plants in the tank. After the eggs are laid, remove the mop
to the hatching tank. Something that most egg scatterers have in common
is that they require very small food when they hatch as the fry are near
microscopic. Again I recommend OSI’s microfood, but a better food would
some very small live food, such as smaller strains of freshwater
paramecium. Most people don’t raise those in their homes, so OSI’s food
is a good, though inferior substitute. Breeding of rainbow fish does not
require a large tank. Most rainbowfish can be breed in a tank 20 gallons
or smaller, though I suggest keeping the adults in a larger tank. Males
tend to look nearly identical to females in color. In some species, the
males will have a bright yellow crest when they are breeding and/or early
in the morning. In most species, the males have a different shape to
their heads. Whereas the females have a rounded head, the male’s heads
are round on the top, but then hit a near 90 degree angle and flatten out
as they head down the snout.
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Killifish are unbelievably beatiful fish that
have to be seen to be believed. |
For
killifish you can also use a mop, but some fish will lay their eggs in the
substrate. It is usually recommended to have either peat or java moss as
a substrate as it will help to hide the eggs from the parents. The
parents should be removed immediately after spawning. Killifish are quite
colorful, that is the males are quite colorful. The females tend to be
rather neutral in coloring. Usually you don’t want to keep more than 1
male in a tank as they fight voraciously. Since most killis are annual
fish, that is they seldom live longer than a year, they grow quickly and
breed freely. The fry are similar in size to rainbow fry, and I recommend
feeding them in the same way.
Tetras
& Barbs are the hardest to breed of this group in general. Whereas
Killis and Rainbowfish breed freely if you just put them in a tank
together, many tetras and barbs require specific water requirements in
order to breed. In fact if the water pH is off by as much as .2 some
tetras will not breed. In general these fish don’t require too much to
breed. They scatter their eggs on the ground, so many people use marbles
or some other porous item on the bottom that allows the eggs to drop so
that they can be safe retrieved after the fish have finished breeding.
Fry are again very small and very numerous. There will be high
cannibalism and death rates unless you can find an extremely small food,
preferably live, to feed them. The freshwater paramecium is a perfect
candidate, but the water it lives in is toxic, so much precaution must be
taken.
Livebearers
The
first type of fish is generally the fist type of fish that fish-keepers
breed. It is often the doorway into the hobby for people, but it is also
under-appreciated. The guppy in particular offers great opportunities for
creating new color strains that are unavailable elsewhere. (for
information on doing so, please read Guppy Breeding--For Experts!)
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The guppy is one of the best known aquarium fish. |
Breeding these fish is not particularly difficult. Livebearer males
posses a gnopodium that makes them easily distinguishable from females.
It resides between the anal fins and is somewhat long and circular. In
many species males are also much more colorful and posses more finage than
the female. This is particularly true with the guppy and some species of
swordtail. In most all livebearer species, the female is much larger than
the male. This is always true when the female is pregnant as it is
carrying 20-400 young that will be fully free-swimming and of a well
matured size when they are born.
To
actually breed the fish, just put some males and females together. As
these fish are very peaceful, you should have no trouble getting them to
breed. Females will carry the eggs for about 24 days at which time the
free-swimming young will be born. The only difficulty you will have is
getting the young out of the tank before they are devoured by the other
fish in the tank. To help in this endeavor, there are many “breeding
traps” that are available commercially.
The young are
easy to raise and can immediately be feed commercial flake that has been
well-crushed.
Conclusion
I've heard it said that if you
never breed fish, you won't stay long in the hobby. Why is that?
Probably because though it's interesting to watch fish, it's not
interesting enough to really capture most people's attention. There is no
challenge to just watching fish. Saltwater aquarists derive their
challenge from keeping things alive in home aquariums that would die
without a lot of care. Freshwater aquarists find their challenge in
breeding fish. I think beyond just the challenge, the amazing behavior
that fish exhibit adds a high interest level to the high challenge level.
I highly recommend trying to breed one of the fish listed here, though it
may take awhile before you have success, it is an exciting process that is
worthwhile for all aquarists to undertake.
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