When they are healthy and well adjusted to captivity, fish eat at a regular time
and become accustomed to the spot where the food is given out. It is advisable to
divide the daily ration into two parts - one in the morning and one in the evening,
for example. The end of the day - 1 or 2 hours before turning the aquarium lighting
off - is usually the most practical for the aquarist. In any event, food distribution
offers a special opportunity to observe the behavior of your residents and check
their state of health. Allowing the fish to come and feed out of your hand is particularly
enjoyable, but take care, because some large specimens have impressive teeth!
If the water is too agitated, artificial or natural food may be dispersed too
quickly and washed to a corner of the aquarium where the fish will not be able to
recover it. thereby creating a potential for pollution. The stirring of the water
must therefore cease when food is being distributed and eaten.
Feeding the fry
When they are born, the fry of egg-laying fish feed on the reserves in their
vitellin vesicle, as their mouth does not open until a few days later. They will
then often accept the fine powders which are available commercially.
If this is not the case. give them brine shrimp nauplii for a few days - newly
hatched nauplii are most suitable for the first two days. After that, they can be
offered nauplii that are 48 hours old.
Daily production over a period of several days must therefore be planned for.
If brine shrimps are unavailable, another option is the production of infusorians.
Live-bearing fish (the Poeciliid family) accept artificial food from birth, and
they also thrive on brine shrimp nauplii. As for marine fish, rotifers, discussed
above, should be used, as they easily fit into the small mouths of the fry.
BREEDING BRINE SHRIMPS
The dry eggs (known as cysts) are available in aquarium supply stores. They must
be kept away from light and moisture. In order to make them hatch, salt water must
be prepared with the following characteristics: temperature 25°C, salinity 35%,
i.e. a specific gravity of 1.023.
Equipment available in aquarium stores for hatching brine
The salt water can be natural or reconstituted with special aquarium salts, or
even with rough kitchen salt (easier for aquarists who do not keep marine fish).
The water can be colder and less salty (up to 20°C and 20%, i.e. a specific gravity
of 1.014), but the hatching rate will be lower (50-60% against 80-90%). Any small
glass or PVC container can be used - bottles, for example - although specialist
equipment is available. The eggs are placed in the still water for a quarter of
an hour, the time required for their rehydration. If we estimate that 250,000 eggs
weigh around 1 g, a tiny amount (the tip of a knife, for example) will produce sufficient
brine shrimps. Aerate the water slightly to produce small bubbles, which will disperse
the eggs, but be careful not to stir the water too vigorously, otherwise some of
the eggs will crash against the sides of the container and will not hatch. The hatching
occurs after 24-36 hours at 25°C, or after up to 48 hours at 20°C. Finally, switch
off the aeration: the empty shells will float to the surface, the unhatched eggs
will fall to the bottom, and the brine shrimp nauplii will be swimming just under
the surface. It is then easy to siphon them off (with an aeration pipe, for example)
and strain them through a small filter (available commercially), or, alternatively,
through the thin mesh of a piece of old curtain, or even a very fine pantyhose.
To make this operation easier, you can group the nauplii together using a flashlight,
as they are attracted by light. You can then go on to feed them to the fry. They
will only survive for a few minutes outside salted water, and they will not eat
on the first day after hatching. If you want to keep them for several days to obtain
larger or more mature larvae, special food is commercially available. This makes
it possible to keep brine shrimps until they are adults.
Hatching brine shrimp eggs in gently stirred water.
A Collecting brine shrimp nauplii through siphoning.
ADULT BRINE SHRIMPS
Adult brine shrimps are sold live in small sealed sachets containing salt water
and air. They are passed through a sieve before being given to the fish, which enjoy
hunting them down. They survive for a few minutes in unsalted water. Brine shrimps
can also be bought frozen.
When feeding, it is important to avoid any overdosing, whether
with artificial food or live prey, such as the adult brine shrimps pictured here.
Automatic food distributor for artificial food. Each section
corresponds to a daily dose.
These are microscopic, unicellular animals, easy to produce in fresh water. They
are usually present in small numbers in an aquarium.
Riccia, a surface plant, gives them a chance to grow, as they find food (organicmatter)
on its leaves. They can also be produced by leaving a piece of potato, a lettuce
leaf, or some paddy rice (unhusked rice, available in grain stores) to soak in a
receptacle containing aquarium water.
What if a fish does not eat?
Sometimes a fish refuses to eat, or appears to be incapable of doing so. It is
therefore a question of finding the cause and eliminating it. A newcomer to a tank
rarely eats on the first day. This is normal, as it feels lost in its new environment.
Small species and more lethargic fish are often dominated by their bigger and faster
cohabitants at feeding time. They must therefore always be fed separately, preferably
with mobile, live prey, once the other fish have been distracted by other food.
In captivity, the fry can be fed with brine shrimp nauplii
and then with fine commercial powders.
A fish can also refuse to eat if it is sick, and this will be reflected in its
behavior, color, and other symptoms which may eventually be seen on its body. In
this situation it must be isolated in another aquarium, treated, and given rich
food comprised of live prey or fresh produce. Sometimes fish can systematically
refuse to eat artificial food, although this is rare in fresh water, but less so
in marine aquariums. There is no point in being stubborn: change to a varied diet
based on live prey and homemade fare.
Paddy rice can be used to produce infusorians. It is "sown"
on the bed or placed in a tubifex worm "feeder".
GOLDEN RULES FOR FEEDING
- Give fish a varied diet;
- give them a little, but often. Two portions a day is ideal. For fry, the
feeding can be more frequent.
- do not wait until the fish are sated and stop eating. Stop feeding once
the ration is complete;
- siphon off any food surplus as quickly as possible, as the leftovers are
Preparing defrosted food before feeding it to large fish.
A MIRACLE FOOD FOR FRY
A hard-boiled egg yolk is added to water in a glass. This forms microparticles
which are then sieved.
Some aquarists use oysters to nourish their fish, which
seem to enjoy them.
This nutritious liquid is then given to the fry, taking care not to put too much
into the tank, as it is always important to minimize pollution. Egg yolk, rich in
proteins and lipids, can be used as a complement or as a replacement for other food.