Back to Fishkeeping Tips 11 "Breeding"
Breeding the Livebearers Found at This Site
(revised Jan. 2016)
Water movement, aeration,
water changes, not overcrowding and abundant
quality food ensure your
best
chance of success. Feeding live and frozen foods,
earthworms or a quality earthworm flake in particular,
seems to increase both the size and health of the
broods. Baby brine shrimp is good, but many adults cannot
feed completely on it, so I do not depend on it for
adult fish. Daphnia is excellent, adult Brine shrimp (frozen
works well), white worms, etc. are all good. Feed at
least twice per day, ensuring the tank stays reasonably
clean. Mulm must be removed when it accumulates- heavy
filtration or water changes do not
eliminate its
negative effect on the fish- it is not "inert".
Inedible, decaying organic material is never good for the fish or
the fry. Not only do these practices lead to healthier
fry, but frequent feeding helps ensure that new fry are
not immediately gobbled up if a female drops before you
are able to remove her. A good diet before a drop
helps guarantee robust, vigorous fry. A poor diet can
lead to fry that are born dead, or that die shortly after
birth, or that develop air bladder problems during
their initial development. (“Belly sliders”)
Breeding traps for swords just don’t work. The traps
are too small, and the female is often distressed
by her lack of movement (particularly when
Java moss is
also added so that babies have a place to hide)
that she may drop early, releasing her fry in an
undeveloped condition, where only a few, if any survive.
Or she will become unable to drop until she becomes
huge, and then she dies- before releasing the young.
A female that is gravid (she is large, and her black
“gravid spot” just behind the belly has become dark)
needs to be moved into a small tank of her own
with some aeration, filled
with fine leaved plants, but not
so much that she cannot swim around. The tank must be at the
temperature of her original
tank,
and filtration (possibly through heavy daily water changes)
is essential. Dirty water compromises
the survival of the new fry. Gestation for most
swords, mollies, platies and guppies is about 25-40 days,
depending on temperature.
One solution that does work has been to create breeders from plastic
"shoebox" style containers or larger
plastic storage boxes that are small enough to sit within a larger
aquarium. The sides and bottom are cut
out, then covered with fine nylon mesh, glued in with a waterproof glue. (see
pic on left of Fishkeeping Tips 11
breeder page). When those are used, be sure to glue a couple marbles to
the side of the breeder that will
face against the aquarium glass, to prevent smaller fish in the tank
from becoming trapped, which can
cause a loss of fish.
New fry
should be fed newly hatched baby brine
shrimp, but can be raised on an artemia substitute or
other fine dry foods. For
swordtails, guppies,
mollies and platies, fry can be raised slightly warmer
(78-80 degrees) to assist their growth.
Goodeid fry should be raised at the cooler
temps- 72-75 that the
adults prefer) Fry
also need to be fed 2-4 times per day at first with daily
water changes of 50%, unless
in a container with adequate
filtration, or in a breeder that sits
within a larger body of water. Leave some
Java moss in with
the fry to assist water quality, but not so much that you cannot see all
of the fry easily to
monitor their condition, or that cause decaying food to
become trapped. Add aeration with at least a mild
air flow from an airstone if possible.
Baby brine shrimp and/or the high
protein fry foods foul the water
quickly, and go bad within just a few hours. A quick
ammonia spike will kill new fry fairly quickly. A rule
that I have discovered over many years, and that
seemingly makes little sense, is that fish that cannot be
seen and monitored inevitably suffer losses, whereas
fish that can be watched and kept an eye on will do
better. I know it doesn't make sense, but we all tend
to neglect the tanks, just enough, that we don't follow
closely.
After 3-6 weeks (depending on species) the
fry can be released in with
the adults. Feed the adults well,
then release just a couple new fry into the tank, watching to see if
they get chased such that they could be
eaten. All adults will chase a new fish to check it out, but when they
determine the other fish is too large
to eat, they will back off. If the adults don't back off, rescue the
released young and wait another week.
The Goodeids- These fish can be the easiest to breed, but building up
their numbers can be a long process
interrupted by long periods of fish not becoming gravid. Some species
will take a break from breeding from
approximately mid September to April, their gestation is around 60 days,
and a young female having her first
batch of fry may only drop 4 or 5 babies. Though the fry are large,
having been nourished by the mother in
utero similar to mammals, they are still often eaten by the adults. The
hiatus some species will take from
breeding over the winter may be triggered by exposure to natural
day-night seasonal light cycles, and
friends with fishrooms without windows, where they can control the light
periods, tell me they don't
experience those seasonal breeding fluctuations.
Many goodeids do not generally
eat their young, but the gravid
females of some species do not do well
when moved to drop their fry. Occasionally after being moved a female
will simply drop her brood stillborn.
I have found that the home-made breeders mentioned earlier will work
when hung in the tank where the
female resides otherwise. Often I simply watch gravid females, then I
will save as many new fry as I can to
raise them separately until large enough to fare on their own.
With Z. tequila the females can be moved reasonably well, but definitely
do best in their own 5 or 10 gallon
to have their fry with lots of Java moss (or fern). Moving to an
unfiltered (but with plants) 2 gallon container
or a breeder can result in the death of the gravid female. Other adults
will eat the fry, and when allowed to
community breed (where
young are simply not removed, with hope that
the population will increase over
time) my experience has been that their numbers will generally decline
over time, rather than increase in
numbers.
Characodon lateralis will increase in numbers when kept simply as a
community, but will be occasionally
eaten. Their broods are often only 5-10 young, and the new fry generally
do not fare well when left to grow
out in an adult tank. However, the females tolerate being moved, and the
young do well when raised up
separately.
The Goodeids will grow out fairly evenly when well fed, but that is not
the case with the Swordtails.
Most swordtail species have an anomoly where occasional males are born
that reach sexual maturity far
earlier than their siblings, an evolutionary tactic that allows some
males to gain access sexually to the
females before the other males in the tank, producing other early
maturing males in the process. The
problem is that these males will be dramatically undersized, often with
poor color and traits that are
not positive for the line. The only solution, until the line is
stabilized (in that the appearance of early
maturing males is rare or nearly nonexistent), is to raise the sexes
separately, then select for the
largest,
most robust fish, culling the early maturing males.
The Swordtails- These cannot all be
considered as breeding the same way, or all given the the same
surroundings and treated the same way to achieve the best results. Some
breed more readily than others,
and batch sizes can vary from 10 to 40, depending on species. Here is
what we have found here, and I will
start from the easiest and most prolific.
Xiphophorus mayae- A sword that is generally
shyer and more "wild" in behavior, they show little aggression
or dominance issues with one another. Males can be kept together with a
grup of females, and in a well
planted tank with adequate feeding they will generally not eat their
fry. Fry should be removed when seen
and raised up separately so they will have easy access to food and
experience maximum growth. They are
considered the largest swordtail.
Xiphophorus alvarezi, Gold - These
are less prolific than the wilds in that they breed slightly less often,
and the batches can produce fry with varying amounts of red markings.
These generally do not seem to eat their
fry, but because some batches from some females can contain fry that are
albino or weaker, I generally remove
the females to their own tank to have their fry, and then raise the fry
separately on BBS. Interestingly,
many adults tend to get huskier and longer than the wild alvarezis they
came from, but rarely surpass 5 inches.
Xiphophorus helleri, Rio Otapa- A
very large swrd, the larger dominant males can be aggressive to smaller
male
tankmates. These get very large, and a big female can easily produce
50-60 fry. They are also fairly prolific.
They may eat their fry, but so many are produced in a tank of adults
that the tank will quickly "crash" if the
fry are not removed due to an overload of organic waste. But there is a
problem. At first many keeping this fish
had sex ratio issues, where entire batches that grew out were all male
or female. After years of experimenting
with this, I have reached 50/50 sex ratios by feeding new young finely
powdered food and live baby brine shrimp.
Feeding a crushed flake will not do the trick. these also take a long
time to sex out. Where the alvarezi may
begin to show secondary sexual characteristics at 4 months, the Rio
Otapas, like the montezumaes, may not begin
to sex out until 6 months or older. The other issue with these is that
unless you have 100 gallon tanks just for
Otapa fry, you will want to watch your tank density as they grow out.
Too many fish will result in their being
stunted, and these will get to be especially large and colorful.
Xiphophorus montezumae- These
are a very different swordtail. When breeding for numbers, the best way
is to breed
them in trios in 10 or 15 gallon tanks with moderate to heavy planting,
frequent feeding and water changes. These
do not eat their fry. they will breed slightly less frequently, and the
batches are generally 10-40 fry. I have
found that the young do not do as well as other swords when it comes to
being raised up in net breeders.
Mortality is higher and they will often develop afflictions when raised
in a confined space. So with the monties
I will either remove the female to drop fry in another tank and raise
the fry separately, or let the female drop
her fry (As they do not eat them), then remove them as soon as they are
seen. these also grow slowly, and may
take 8 months to a year to fully sex out and produce fry.
Early Maturing Males
All of the sword species, and some molly species will produce Early
Maturing Males, and these must be removed as
soon as they are seen. Early maturing males are an adaption made by
these species, where a percentage of males
will sexually mature earlier than their brothers, and do not use a
courtship behavior to mate. The result is a
smaller size, but you are able to get your genes out there before anyone
else. All of the Xiphophorus swords I
have worked with have this, and breeding the trait out of the line can
be done, but they must be removed over
many generations for the trait to disappear.
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