Page 235 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

REPRODUCTION AND BREEDING 233

clownfish eggs, avoid exposing them to the air, and do not More commonly, fry are fed on the larvae of marine organisms
dislodge them from the rock to which they are attached. The called rotifers, which you can culture at home. If this is not
fry hatch tail-first, and if an egg is not firmly glued in place, convenient, use frozen rotifers as an alternative, but always
the fry will be unable to wriggle free of its shell. With its gills make sure that they are thawed before you add them to the
still covered by the egg casing, the fish will suffocate. tank. You should be able to see the fry feeding—the young fish
The eggs of clownfish and other egg-depositors typically will curl their bodies into an S-shape and then lunge at their
hatch after dark. If you shine a light on the water’s surface, quarry. As their gut starts to fill up with food, the underside
the fry will flock to this spot, and you can collect them in a of the body takes on a whitish hue.
cup. (Do not use a net, which will damage their delicate fins A culture of brine shrimp will also need to be set up as a
and gills.) Transfer the fry to a pre-prepared rearing tank, with follow-up food. Introduce small amounts of brine shrimp to
water conditions identical to those in the main tank. The tank the diet of the young fish after the first three days or so. Brine
floor should be bare, so that waste food can be removed easily. shrimp eggs can be bought complete with a hatching kit (see
Place a guard on the heater to protect the fry. Good water p.68). When the white stomachs of the fry turn reddish, you
flow is vital to oxygenate the water sufficiently and to circulate will know that they are eating brine shrimp rather than rotifers.
particles of food. A power filter is unsuitable, since it may trap Other foods, including powdered marine flake, can be
fry; a sponge filter, supported by an airstone, will be sufficient. introduced as the fish grow larger, typically once they start to
gain adult coloration. When the young are
Feeding regimens for young fish about ⁄4 in (6 mm) long, they should
1
Your breeding efforts will fail if you do not have enough be transferred to a tank with more
food of the right size for the fry during their first few days. effective filtration.
The young fish will be able to consume only tiny food items,
which must be evenly distributed throughout the rearing tank
at a relatively high density, since the fry are not able to swim
far at this early stage in life. In the wild, newly hatched fish eat
plankton. Catching plankton is feasible if you live
near the sea, but you will need a special net with a mesh of
approximately 50 microns. Although this may be appealing because
it is a natural feeding option, harvesting plankton from the sea
increases the risk of introducing disease into the aquarium.

ROTIFERS FOR MARINE FRY
The most popular rotifer for rearing marine fry is Brachionus
plicatilis. Culture rotifers in a small tank on unicellular marine algae,
which requires good lighting, or on yeast. Regularly check water
samples from the culture tank with a hand lens. When there are at
least 25 rotifers per teaspoon,
you will have a dense enough
concentration to sustain the fish.
Feed the fry two or three times
each day. Gentle currents in the
rearing tank will keep the rotifers Expelled by muscular
afloat so that they are accessible contractions, up to
to the fry. Siphon the tank floor 100 free-swimming
daily to prevent any buildup of sea horse fry start to
uneaten dead rotifers, which will emerge from an adult
impair the water quality. male’s brood pouch,
six weeks after the
A rotifer, shown here magnified eggs were deposited
50 times, is half the size of a brine there by the female.
shrimp. This female is carrying eggs, The male takes no
which are the gray smudges at the further interest in the
base of her tail. Some female rotifers fry. Sea horse fry will
are mature within a day of hatching. take brine shrimp as
a first food.

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