A small
aquarium could be considered to be between 30cm (12") and 60cm (24") in length.
Any smaller than this range and it is too small to keep any fish in, regardless
of their size, unless you are an expert aquarist. Small aquariums need basically
the same equipment as larger tanks so a heater (assuming tropical fish are kept)
and filter are essential. A good light is also required if you wish to grow
plants, or see your fish at their best.
The stability factor
In comparison to a fish's natural environment, a small aquarium really is small,
providing the right fish are chosen however, the space factor is not a problem.
If the environment is sound and there is enough space for the fish to act in a
natural manner, most small fish will thrive in small tanks. Some fish, such as
the Siamese Fighting Fish (Betta splendens), seem to even prefer smaller
aquariums, although this is more likely to be to do with a dislike of open
spaces or busy communities.
The major factor to consider in regards to the well being of the fish in small
tanks is the smaller volume of water, and the effect this has on the
environment. In a large volume of water, changes in chemistry caused by the
addition of a pollutant are much diluted in comparison to the same level of
pollutant being added to a smaller volume. To put this another way, the
introduction of one gram of a substance to a 100 litre volume of water gives a
concentration of 1mg/l (one milligram per litre) but the introduction of the
same amount to only 10 litres of water gives us a concentration of 10mg/l (ten
milligrams per litre). What this means is that any detrimental changes caused by
common factors such as overfeeding, overstocking, bad maintenance and so on, are
greatly increased in smaller aquariums. The only way to counter this effect and
keep top conditions is to carry out a regime of regular water testing, proper
maintenance, and most importantly, correct feeding levels.
Maintaining a small aquarium
Looking after a small aquarium is fairly easy and the basic principles are the
same as for a larger aquarium, but less! Water changes are the key factor to
consider; small and often is the rule here. Far to many fishkeepers routinely
clean the aquarium every month or so, which usually involves an almost entire
water change. The only time in which you should ever change more than half the
water in an aquarium is as a response to an emergency situation. In a small
tank, a large water change has a greater effect, and can cause various
environmental factors to become unstable. It is good practice then to try to
keep water changes at no more than 10% at any one time for small aquaria. If you
have to increase the water changes due to improper water conditions (which may
occur whilst the tank is new) then it would be better to increase the frequency
rather than the amount. Changing 10% of the water each day for three days is
much better than one 30% water change.
Filter maintenance
In smaller aquariums the filter is often a fairly basic unit with a simple pump
and piece of foam which just needs a fortnightly rinse in water from the
aquarium (never use tap water as the chlorine will kill the useful filter
bacteria) It is a good idea to cut this piece of foam in half so that when the
time comes to replace the sponge, one half can be changed a few weeks before the
other, giving time for the bacterial population to colonise the new half.
If possible, try to get a filter which allows room for additional carbon, or
phosphate removing media; this will help in the long term control of water
conditions.
Plants in small aquaria
Live plants are very beneficial in small aquaria as they have the ability to
take up dangerous pollutants including ammonia, nitrites, and nitrates. This is
extremely useful in small environments where water quality fluctuations are more
likely, in this situation the plants almost act as a 'safety net', ready to soak
up any excesses. Most small aquariums with fitted lights are ideal environments
for some of the smaller aquarium plants to grow in; all that is required is a
good, fine, and preferably nutrient rich substrate for them to root in.
Feeding
The single most important factor in most aquariums, but especially smaller
aquariums wellbeing is the quality and level of feeding. The food you place in
the aquarium is the main, and in some cases only, source of waste produced in
the aquarium. The less you feed, the less waste is produced, and the better the
environment will be. Of course, your fish will need feeding correctly so a
balance must be made between providing them with all the food they require,
without overfeeding. A good rule to follow to achieve this is to feed your fish
as much as they will eat in only a minute, without any food sinking to the
bottom of the aquarium or being left over. Standard flake foods are a good
choice for the fishes main diet, most flake foods produce less waste products
than some other food types so it is wise to stick to this food type during the
first couple of months. Once the tank is a few months old or when you start
adding fish such as bottom dwelling scavengers or algae eaters, you will need to
start feeding some different types of food and a varied diet will help your
fishes overall health over a long period
Fish
Arguably the most important element of the aquarium is the fish, and choosing
the right fish can be tricky given the wide range available. For small aquariums
it is not a simple matter of choosing small fish, although obviously this is a
factor. It is important to consider that the fish you choose will have to live
together in a restricted space, so even a slight hint of territorial behaviour
or a boisterous nature could become a big problem. Common mistakes include fish
like male Swordtails, dwarf Gouramies and dwarf cichlids, which may all turn
into tank bullies. Fish that are constantly active, like Rosy barbs, or Danios
will often do well in smaller tanks, but may annoy other tankmates with their
constant movements.
For the lower regions of the aquarium, and to make a good cleaning crew a
mixture of small scavengers and algae eaters can be used. Small groups of
Corydoras sp. make ideal scavengers whilst Otocinclus sp. and small
Peckoltia sp. are good small algae eaters. Japonica Shrimps (Caridina
japonica) are excellent additions to small aquaria and a group of these
shrimps are also more likely to be seen in a small tank. Some barbs will also
inhabit the lower regions, swimming amongst or just above the plants and décor.
Good choices for smaller tanks include the Cherry Barb (Puntius titteya),
Checkered Barb (Puntius oligolepis), and Fiveband Barb (Puntius
pentazona)
For the midwater regions, shoals of small tetras are always a good choice, but
avoid nippy tetras such as Red-Eyes or Serpaes. Neon Tetras (Paracheirodon
innesi), Glowlights (Hemigrammus erythrozonus) and black or red
Phantom Tetras (Hyphessobrycon sp. ) should do well, but neon's are best
added once the tank is well matured.
For the surface levels, although they will swim elsewhere, Platies (Xiphophorus
maculatus) and Mollies (Poecilia sp. ) are always popular. Guppies
are also popular fish but I would not recommend them for small aquariums due to
their weak nature caused by intensive breeding.
Other good fish for small tanks include the Honey Gourami (Trichogaster chuna),
Coolie Loach (Pangio kuhlii) and Harlequin Rasbora (Trigonostigma
heteromorpha) A single male Siamese Fighting Fish also makes an excellent
addition and will quickly become the most noticed fish in the tank.
