Mouthbrooders:
Collecting and Raising the fry
Age matched fry from mbuna and
haps
Raising
the fry of any fish is a very pleasing and rewarding procedure.
Although it is perhaps one of the most difficult, delicate
and painstaking parts of fishkeeping, very few hobbyists will
ever complain about it. The mere fact that you have fry to care for
means that you succeeded in providing this particular species with
almost what it needed to feel comfortable so as to spawn and then
carry the eggs and fry.
There
are many ways fish use to spawn and then take care of their fry but
this article will focus on Malawi cichlids which show the most
advanced form of parental care; mouthbrooding. This article will
just mention some facts that come from my experience and will
hopefully help other fellow hobbyists to avoid some pitfalls.
Cichlids from Lake Malawi do their best to help us to raise their
fry. Instead of laying thousands of eggs and then guard them in the
tank (causing all sorts of trouble) they produce a limited number of
eggs (150-180 at most, in large, mature species). This is because
mouthbrooding ensures that their fry, when released will be already
0.8-1 cm in length and far better “equipped” to cope with life.
In contrast, other cichlids produce thousands of eggs just to
compensate for very high mortality rates.
It worths mentioning that in a recent article in "Cichlid
News" (April 2000), Ron
Coleman refers to a total loss of 68 broods out of 87 spawning
of Neolamprologus mondabu (Lake Tanganyika). This shows the
importance of mouthbrooding for the fish.
Cheilochromis
euchilus - carrying female
Mouthbrooding
is an advantage for the hobbyist, too. He immediately knows when a female
is “carrying” and all he has to do is to net it and place it in
a tank of its own - if he wishes to raise the whole brood. A carrying female is easily identified: it will
refrain from eating or will carefully eat very small quantities, it
will occasionally look like “chewing” (actually she aerates its
fry) and will try to avoid fights and quarrels. Even very active
species will look a bit milder and far less active - sometimes you
may even see it staying in a dark part of your tank or close to the
bottom, behind the filters etc. It will usually
keep the fry for 3 weeks and then release them. Please take note
that the duration of the carrying term depends on the water
temperature. Thus, at 24oC the duration may reach 4 weeks
while at 30 degrees it may be as short as 17 days. You should always
take this factor into account when making your calculations
otherwise you may end up with the fry released in the main tank. In
all cases, the fry is completely developed when released. Some
species (notably Labidochromis caeruleus, the electric yellow
labido) use to carry much longer. It is not rare for these species
to carry for more than 30 days (I have personally witnessed a 41 day
carrying period).
You
should keep in mind that some species are “seasonal” spawners.
Thus, my Sciaenochromis fryeri will start spawning in the end of May
and will do so three times (till the end of September) every year. It
will not spawn during the rest of the year. Age plays an important
role on the frequency of spawning. The fish will spawn regularly for
some years and then, as it gets older it will spawn less frequently.
The size of the brood increases as the fish matures. Usually the
first couple of attempts will not be successful but then nature will
find its way. In some species (very common among the haps), the male
takes considerably longer to reach sexual maturity than the female.
This will also lead to some unsuccessful spawns.
Some
fish will not spawn if the environment is not appropriate. Haps
(especially large species) do not feel very well in crowded tanks
and even if they try to spawn, other haps (natural predators) will
lurk around to interrupt the spawning and eat the fry. Thus, you may
see a spawning pair but not a carrying female after that. The
presence of an aggressive hyperdominant species (especially in mbuna
tanks) may prohibit milder species from spawning at all. It is not
rare to see many species spawing on the spot once a hyperdominant
male is removed from the tank. After removing a 14 cm male
Melanochromis auratus and a 15 cm male Melanochromis chipokae from
my tank, I observed five carrying females within one week, females
that had never spawned before. In conclusion, the fact that a pair
will not spawn may just mean that the conditions or the nature of
the fish is such that will not allow it to spawn in that particular
tank. There are many more issues related to this matter. It seems
that the females in nature choose their mate. They will refuse to
spawn with an inferior male and they select the one that looks
"promising" by the size and shape of the nest (spawning
pit) it managed to built - among other factors. This is very rarely
seen in the artificial environment of the tank in which the female
doesn't have any other options and building a pit is usually not an
option for the male. However, some times a female will cross breed
with a male from another species even if a male of its own species
is present in the tank.
Some
people use to “strip” their females. This is not the natural way
to go and should only be done if the mother is sick or has a long
history of unsuccessful carriages – and you badly need the fry.
Stripping a female may result in the release (spitting) of immature
fry with the yolk sacs still attached, an easy meal for the rest of
the tankmates. It may also result in injuring or stressing your
female too much. Even if you are successful in stripping your female,
the females raised this way (from stripped mothers) have a much longer history of spitting
or swallowing. It is now widely accepted that mouthbrooding is not
only a way to protect but also the best way to aerate, feed and “educate” the fry.
Nobody can replicate that! Moreover,
the stripped females give fry that are more prone to disease.
Netting
them may sometimes be easier said than done. Chasing a small sized female,
which hides under every rock in your tank until you remove all of
them, is not a rare situation. Things are a bit better with haps,
mainly because of their larger size. One thing that has to be noted
here is that haps should be handled more gently than mbuna. Some
haps will immediately spit their fry if stressed too much. This may
happen in your net – which is good news - but it may also happen
out of it (which is good news for the other haps but not for you).
It is always better to use two big nets (that are at least 1,5 times
wider than the overall length of your fish) one to chase the fish
and the other one to catch it. The method that works best for me is
to leave one of the nets still and "guide" the female in
it. Then - when the fish is almost in the still net - with a quick
move I net her. Once netted be as gentle as possible with it. It is even better to leave the nets
for 10 minutes or so in the tank (so the fish get somehow used to
them) and then try with gently moves to net the female. You will be
amazed to see that sometimes you may net a female with very gentle
moves and the least of stress to it. Among the species I have
spawned the worst spitters are Cyrtocara moorii and Nimbochromis
livingstoni. In contrast, my female Sciaenochromis fryeri will stay
almost motionless, waiting to be netted. There are no rules on this
one. One of the most experienced hobbyists I know of, has the hell
of a time every time he has to net his female fryeri. He always ends
up tearing apart his tank or he just quits the game. You can always
see all size of Sciaenochromis fryeri fry swimming in his tank – a
sign of failed attempts to net the female.
Own
tank vs. the main show tank? Well, it depends. Usually, most
hobbyists want to be able to see the way the female gradually allows
the fry to stay out of its mouth or the way it will take them back
when the enemy (you) approaches the tank. If mortality rate is the
only thing that interests you then the separate raising tank is a
must. However, even if the fry is released in the main tank, some of
it will survive. A mortality rate of approximately 5% in an
overstocked mbuna tank with few hiding places is the most you can
expect. However, you may be able to get a 30% survival rate in an
understocked mbuna tank with plenty of hiding places correctly built
and placed. If you have such a tank, not removing the carrying
female is always a good option. In a tank with adult piscivore haps
things are far worse. In such a tank (even with hiding places) the
survival rate is always very low. It usually is less than 1%. This
is because unlike the mbuna tank, in which fish reaching the age of
4 months (sized 3-4 cm) will probably grow to maturity, in a tank
housing large piscivores, the danger is always there. Even fish
sized 8 cm may be eaten on the spot. Unfortunately, haps don’t
grow much quicker than mbuna, so they must reach the age of 1 year
before they are safe. In all cases, the more broods are released in
the same tank the lower the survival rate, because the best hiding
places will already be occupied so the newly released fry will only
find very risky spots to hide. Just a quick note : in a raising
tank, the most efficient fry killer is a strong filter which will
trap the fry.
A way to deal with it effectively is to wrap the filter in nylon
mesh. The same precaution should be taken when changing
the water of the raising tank or vaccuuming the gravel in the
main tank.
Plastic
hatching compartments or artificial plexiglass dividers are just
another way to keep fry of more species in the same tank volume.
However, this has some disadvantages. Keeping them too crowded (if
the species allows for that) results in a reduced growth rate,
unless you follow the discus raising procedures = huge water changes
as often as possible. The floating nests will allow you to keep more
fry but they will take centuries to grow. On top of that, the
hygiene of the water is very poor no matter how hard you try to
improve it and the outbreak of a disease, if it happens, will have
devastating effects on the population. This is because the water
flow in the floating nests is far less than needed and the fish is
very crowded so the pathogen will not need to travel a lot to find
is next victim. Usually, I just select a few species to keep and
raise their fry and I let the others in the main tanks. You can
always mix fry from two different species as long as their age is
more or less the same and their melanin pattern is different.
Otherwise you will have a big problem when you will have to tell
which is which. Thus, it is a good idea to keep species with
blotches (Nimbochromis fry) with other species with bars (Protomelas
taeniolatus or Cheilochromis euchilus - see photos below). It is definitely not a good
idea to keep the P.taeniolatus fry with the C.euchilus fry in the
same tank. While young (less than 6 months) their main difference is
their color (silver vs. gold) but you can’t possible rely on that,
not can you wait 15 months to be sure.
Cheilochromis
euchilus fry in their own raising tank
Growth
rate is a complicated matter, which is related to a lot of factors.
Among them, the key issues are water temperature, feeding habits
(frequency and type of food), frequency of water changes, filter
capacity, filter precautions, hygiene precautions and maintenance
(e.g. dead fish is removed on the spot, fish waste is regularly
removed, filters are regularly cleaned etc.). The higher the
temperature the quicker the fry will grow. This is mainly because
their metabolism in increased and has the drawback of a reduced life
span and an increase in aggression levels. When we discuss the
temperature issue one needs to have in mind that this should not
reach very high levels. The higher the temperature the less oxygen
is dissolved in the water which may kill (suffocate) your fish. On
top of that, different species will tolerate higher temperature in
different ways. Thus, while discus will thrive at temperatures
exceeding 30oC, cichlids from Lake Malawi will not feel
comfortable at any temperature over 29oC while their
Tanganyikan counterparts will tolerate even lower temperatures (28oC
at maximum). Frequent feeding, frequent water changes, excellent
hygiene and tank space all have a positive effect on the growth
rate. If your raising tank is not permanently working, an ammonia
peak will definitely occur and kill all the fry unless you perform
large and frequent water changes (usually I change about 85-90% of
the water every week). This must be accompanied by regular ammonia
testing to ensure that the biological filter works (ammonia levels
drop) before you can gradually decrease the frequency of water
changes. The fact that normally you have to feed very frequently
(5-6 times daily) makes this precaution a must. Even a partially
established filter may not protect your fry under this feeding
schedule.
continued
in next page
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