Benefits of an aquarium:
a) It makes home homelier. If it is kept in a classroom, it makes the class livelier.
b) Aquarium scene entertains guests. A decent aquarium always attracts eyes.
c) It can bring social activity (interaction with other enthusiasts).
d) If we have some plants at home, we can water them with aquarium water.
e) Well, it may be useful during fire (e.g. to wet a blanket) but make sure the aquarium is far from the power socket or else it can be a cause of short-circuit fire itself in case of leak.

The hobbyist mindset in setting up and maintaining a self-sustaining tank: to mimic the nature. Simulate the habitat in the interest of the inhabitants to make them as happy as possible. A tank that nearly achieves ecological balance (able to metabolize waste) can be considered a biotope. Unlike other type of petting (in rare cases a dog can get along with a cat), multiple types of organism can be kept together in an aquarium.

If you are a beginner aquarist, you should keep a log of what you have done and your observation on the fish husbandry. Focused attention on one aquarium gives more chance of success. Do not be pushed by the sudden whim to keep two or more aquaria unless you are really serious about it such as you want to do experiment or something.

In the morning before you go to work, feed the fish and see if there is any problem in the tank.

You may see some scientific names here for the ornamental fish and plants I mention here. I include that because some fish has different common names between two regions. Scientific name is more specific. When you type the scientific name in any search engine, you can be sure the search result, together with fish picture, is precise.

This manual is more than adequate for Siamese Fighting / Fighter Fish (Betta splendens).

Content:
Choosing tank
Filter
Air pump
Light
Plants
Gravel
Other things to put in
Location of the tank
Fish
Fish food
Supplement

Choosing tank
For beginner, the bottom of the tank should be reachable by hand so that it is easier to organize the tank. Tall shape is less desirable for fish compared to long shape. It should have an optional cover as some fish like to leap out.

Fish bowl is not that good. The more water filled in after half level, the smaller the water surface area for air exchange.

How much should the minimum capacity be? It is rather subjective. Some people calculate that based on the total length of fish they want to have. Some people do not have ample space at home. In this matter you do not have to be influenced by others. Custom to your own condition. You may kick out the option of buying a tank stand by identifying an existing strong shelf etc in your house to place the tank. Then with the size of existing support for tank in mind, you know what volume of tank you need when you are at the shop. I have 20 liters on top of a 42 centimeters width small bookshelf. The little fish seem to be happy with just 20 liters. Do note that bigger tank is chemically and biologically more stable and the tendency of cloudy water is slightly lower relatively. But bigger tank also means you have to rub off bigger area of algae. Algae affect appearance so you should rub / brush them off immediately whenever you see them or else it defeats the purpose of having an aquarium.

Tanks with rounded corners although more expensive but they look much more better than tanks that have joined corners. Tank with joined corners have more seams so leakage has higher possibility to happen. Tank with rounded corner is usually made of acrylic. Acrylic is good if you have heater in the tank because it insulates better than glass. The drawback of acrylic is it can be scratched easily. I get a glass tank because I know I will scratch an acrylic tank when I rub algae off the tank wall.

Filter
The agitation of water surface by a filter promotes air exchange and prevents formation of thin protein (from fish food etc) film on water surface that blocks air exchange.

Heavy filtration (for example two filters) is needed if you are going to have Goldfish. But note that heavy filtration with strong current in a small tank may cause the fish to have internal injury.

There is a type of top mounting pump filter in which water is pumped up into a long horizontal box that contains filter media. I do not use it because there has been reports on fire risk.

I recommend an external hang-on-tank siphonic overflow power filter with bio-wheel (in short, hang-on filter). External means more space in your tank. It simply hangs on the edge of your aquarium without any extra mounting pieces. Wet and dry exposure on its bio-wheel lets beneficial aerobic bacteria do their job effectively. Note that although internal under-gravel filter is better for bacteria colonization but it has more other weaknesses.

Fill the filter with water first so that the siphon tube works. Dip the tip of the siphon tube into tank water. Switch on the power. The power is just enough to siphon up water from your tank to further fill up your filter until it overflows naturally into your tank like a tiny waterfall thus there is no motorized strong current that agitates your fish. The water bath with just right water movement (not idle but yet not strong) in the filter is ideal for nitrifier colonization besides the bio-wheel. You can put something (for example rounded gravel) into the filter to increase the colonization surface.

Hold a cleaning sponge etc at water outlet when you want to pull out the filter pad for rinsing because some dirt will flow out of the filter. The filter pad should be rinsed in the water that is scooped out of the tank for change, not in tap water to preserve the beneficial bacteria. Do not throw the filter pad away because beneficial bacteria are developing on it. The filter pad needs not to be replaced unless it has become torn. Bio-filtration improves with age so do not wash your filter. Whenever you view your fish, be sure to see your filter too. Always watch water level to ensure the tip of the siphon tube is underneath water surface. If there is no water in the filter, not only the motor will heat up, the bacteria colony in your filter also will be destroyed. Just in case if this happens, turn off the power immediately to let the motor cool down and it may still function. Take out the impeller to see if it is tangled by something (I discovered human hair on 28 Aug 2006). If it stops for a few hours, the water actually starts to turn cloudy. And you will start to amaze at the efficiency of this simple filter without much filtering material in which you doubt it when you first open the package. It is actually doing biological / bacterial filtration rather than mechanical filtration. If the flow rate decreases after a few weeks, thoroughly flush the siphon tube. Also take out the magnetic impeller to brush and wash away the slime.

If there are a few sizes in the shop, choose the biggest one because:
a) more beneficial bacteria can dwell in it
b) bigger impeller will not get stuck easily
c) bio-balls for the colonization of beneficial bacteria can fit into it.
d) since the water flow is not strong, the bigger the diameter of the siphon tube the better so the siphon tube cannot be easily clogged by leaves from your plant etc. Then you do not have to always take out the siphon tube and let strong tap water enter the tube to flush out the debris.

This hang-on power filter is not big enough and has no bio-wheel

You will notice that with a hang-on-tank filter the water level in tank actually decreases quite fast due to evaporation. If you have extra budget, my next recommendation is a canister filter. Modern canister filters (ones you see nowadays) were first produced by Eheim.

Air pump
The reason I talk about air pump after filter is because I think it acts as a supporting role to filter to further aerate the water. The more air exchange the merrier as not only fish needs oxygen but so do the beneficial bacteria. The smaller the tank the bigger the need of having an air pump for aeration because less water means less oxygen. Oxygen is also needed by plants when there is no light. Plus the bubbles look cool too, hehe. I personally like to put the bubbles at front left or right corner.

Get a pump with double outlet and transparent cover. The transparency does not have anything to do with effectiveness but from my experience that version is always of better quality. Choose the shop that gives you a length of air hose and an air stone for free. Why is air stone important? It
a) makes the air bubbles smaller so that more air is exchanged.
b) keeps the air pipe from floating.

To prolong the durability of the pump, turn the air pump to the max only when there seems to be something wrong with the tank environment.

If you dislike the pump vibration rattling noise and you have extra money, you can go for an aerator. Some even have lighting for the bubbles.

By the way, if you do not keep an anabantoid but you see a lot of suds (tiny bubbles) on the water surface, it just indicates that a water change is needed.

Light
Besides viewing pleasure, lighting is essential for underwater plants. The light should be white-colored (like sunlight). If the light is unsuitable for plant, the aquatic plant will hardly survive. Thus botanic light should be used because it has special wavelength. If the botanic light bulb cannot be found in the local store, then take the one that is 120W. Brighter light also makes the tank look great. UV sterilizing light should not be used as it may eliminate the nitrosifying and nitrifying bacteria in new tank. They are photosensitive, especially to blue and ultraviolet light.

If your tank does not have a lid that houses the lamp and the fish you are going to keep will not leap out even without cover, choose light fixture that looks like a reading lamp that is clipped on the edge of the aquarium and has flexible neck. The flexible neck must be made of stainless steel. It is easier for you when you want to clean the tank, just turn the the lighting hood away. Also to avoid spooking the fish, before switching it on you can turn the lamp away and then turn the lamp slowly to the aquarium again after switching it on. Submersible lamp is not that good because it makes tank cleaning awkward.

Switch off the light if you are not going to see the aquarium again for the rest of the night. Also note that there is no point to switch on the light when the water is cloudy or green.

Plants
Underwater plants are essential as they:
a) absorb nitrate from the tank water and give more oxygen (there will never be enough oxygen in the tank). If you do not have plants in the tank, you will need to use artificial method to get rid of the nitrate (e.g. eliminating the source, ammonia, by using zeolite).
b) may help to a small degree with stunting algae as they draw much more nitrate.
c) provides hiding place for fish. Fish do not really like to swim in open water.

I think it is better to get the type with broad leaves because
a) some fish just like to eat plants with fine leaves.
b) broad detached leaves will not be sucked into the the power filter's siphon tube so you do not have to flush the siphon tube to clear the blockade.
c) theoretically it can survive more easily because broader surface harvests more light.
d) The tank looks messy with detached fine leaves.

For me plants that are hardy are plants that do not need much light. Java Lace Fern, or just Java Fern (Microsorium pteropus) is an example. It can survive in low light. In fact its leaves may turn transparent if there is abundant light. It prefers its root to be tied (with rubber band, cotton string etc that you can find in the house) to rock or driftwood than to be buried in substrate. The root will stick on driftwood itself finally. Another plant that does not need much light is Anubias. It also likes its root to be tied to stone or bogwood.

If you really want to choose fine-leaved plants despite of the weak points mentioned about, there is a fine-leaved plant that is rather fast-growing if there is no other plant to compete for the nutrient so it is even suitable for betta fishbowl. Its leaves have rounded tip. It can be grown free floating or rooted. Its proper name is Egeria densa. Other name: Elodea densa (but it is not really elodea because it produces 2 to 4 flowers but Elodea only 1, and it has large white petals versus small on Elodea, and it is good for cool to tropical aquarium whereas elodea is good for cool only), Anacharis densa (but actually anacharis is a general name for both egeria and elodea). Moniker: waterweed, Brazilian elodea.

Floating plants like water lettuce (Pistia stratiotes) are not really suitable for indoor aquarium because they need extensive sunlight.

Note that if you keep goldfish, the plants will be easily stained by goldfish's excrement even with heavy filtration. Also plants may be covered by algae but you cannot keep an algae eater with a double-tail goldfish because the algae eater may harass the slow-moving double-tail goldfish. You will need to brush the stain off the leaves occasionally to reveal the greens. Also goldfish may bite roots that are exposed, causing the plant to die.

Fertilizer is not needed. The plant can survive on botanical light and nitrate converted by bacteria from fish excretion.

Gravel
Gravel is to hold underwater plant in place. Even if you have only floating plant that does not need to be held in place, the gravel can be for colonized by nitrosifying bacteria (i.e. Nitrosomonas europea) and nitrifying bacteria (genus Nitrospira, previously commonly thought to be Nitrobacter. Nitrobacter does well in soil instead). Nitrosifying bacteria oxidize ammonia to nitrite while nitrifying bacteria process nitrite to less harmless nitrate. Simple biochemistry. Gravel which has naturally smoothed and rounded surface is better for colonization. Also with gravel, fish discharge will not look so apparent on the tank bottom.

The layer must not be too thick but just enough to hold plant. If your plants are uprooted continuously, add more gravel. If the layer is not thick enough to hold the plant and you heap the gravel around the root, the gravel layer will flatten itself the next day and the plants float. Frequent replanting will hurt the plant.

Do not choose gravel that
a) has powdery surface because it may make tank water cloudy.
b) is dyed or coated. It is not natural. Also the color may leach into the water.
c) has sharp and pointy edges.

I personally like naturally rounded light-colored and semi-transparent mixture small gravel with average diameter 3mm. Anything more than 3mm may trap dirt while anything less than 3mm has insufficient gap (less aerated) for beneficial bacteria to colonize, easily gets packed up and may be sucked into the hang-on filter jamming the impeller (that is why sand is not suitable). You may riddle the gravel with a shallow plastic basket as a coarse sieve (choose your own desired pore size) to separate out sand and tiny gravel.

Other things to put in
With plants and light, the aquarium already has good appearance. Stone and shell are not essential in aquascaping. In fact they decrease the space in the tank and obstruct your hand when you rebury uprooted plant. A few ornamental stones are OK but do not overdo it. And you should shift the stones from one corner to another sometimes because dirty things may accumulate under the stones so you want to aerate the spot. Shell may develop something bad inside it. Dead fish may also trap and rot inside too. Most shells are from saltwater and it is kind of odd to put some saltwater shell in the freshwater aquarium.

If the aquarium is big enough, a cave (for example a coconut shell) can be put in. Fish like caves. The cave should not be too deep - you should be able to see everything inside.

Put in sinking wood if you intend to keep a pleco.

Location of the tank
Do not put the tank near the place where we will walk always (e.g. beside the exit of a corridor, beside a door).

...

So now you have set up a tank. New tank syndrome must be alleviated. Let the tank stabilizes itself first with the equipment switched on (including light) a few days before adding fish. This lets the tank environment stabilize and lets the plants establish roots. Add at most three hardy fish first for example Black-skirt Tetra or Siamese Fighting Fish (but you can only keep one Siamese Fight Fish in a tank). Then add more fish slowly after one week. Do not add many fish at one time to prevent ammonia spike. Do not overcrowd the tank. My own reference for fish number estimation is the tank bottom available area. I ask myself this question: "Is there enough area for every fish to sleep?". Another question is: "Will there be enough oxygen for all the fish if in case there is power or equipment failure?"

Fish
What do you want? Do you prefer fish that swims
a) around actively even you do not approach the tank?
b) just a little even it is totally healthy?

For me I think when the fish with sucker mouth is sucking the tank wall, its mouth movement seen thru the glass looks cute so I will get one of those right after algae appear on tank wall. I also like to have some unexpected babies in the tank so I will get livebearers. If you are in temperate zone and you want an unheated tank, you can choose goldfish. If you like chasing scene, try Tiger Barbs. Aquatic creatures are really exotic.

Do not choose fish that
a) lives in saltwater (they are for pro only).
b) are carnivorous (except Betta).
c) do not eat cheap pellet food.
d) can grow to more than half foot for example single-tail goldfish, common Pleco etc unless you have a very big tank. Note that there are a few species of common Pleco: Hypostomus plecostomus, Hypostomus punctatus, Pterygoplichthys multiradiatus and Pterygoplichthys pardalis.
e) are for feeding big fish. Though they are cheap but they may have disease or parasite like ich. You can get them if you have a quarantine tank (high concentration of salt). Feeder fish are sold in big number but if you buy other fish you can ask the shopkeeper to give you two feeder fish for free. But they are usually single-tail goldfish that will grow to more than half foot. I still do not recommend getting such fish.

Price of fish at aquarium shop although higher than market but
a) you can choose fish and number of fish.
b) you can get the water from the fish tank itself. A fish that is put into new water will be physically shocked and may die the next day after reaching home although it still swims actively on the first day. Repeating sales tactic.
c) the oxygen is new as the bag is not pre-packed as most hawkers in the market do.
d) you can build up the relationship with the shopkeeper and ask for something extra or discount from time to time.

Healthy fish
a) do not swim by wiggling like snake compared to the other fish of same kind.
b) do not have torn fin.
c) have all fins stretched out vigorously.
d) have good appetite, You definitely want to pick up fish that seems to be eating something from the bottom or the wall inside the aquarium. Do not settle with fish that is inferior. I once bought some Guppies but I was satisfied with only 2.

Each category of fish usually has many varieties to keep you busy collecting. You should decide what category of fish tank you want to have. Example:
a) Guppy (Poecilia reticulatus) tank.
b) 'Smaller Tetra' tank. Although they are compatible with Guppy too but they are less hardy than Guppy so I do not put them in one tank with Guppy.
c) Endlers (Poecilia wingei) tank. It should not be mixed with Guppy as cross-breeding produces infertile offspring.
d) A tank with Platy (Xiphophorus maculatus), Molly (it needs a little salt), Long-fin Swordtail (Xiphophorus hellerii), Dwarf Gourami (Colisa lalia), Long-fin Black-skirt Tetra (Gymnocorymbus ternetzi), Long-fin Rosy Barb (Puntius conchonius, some say it is not compatible with Black-skirt Tetra but I think it is OK), Albino Red-fin Shark (Epalzeorhynchos frenatus).
e) Fantail goldfish tank. Goldfish tank will need heavier filtration as they are very messy. Goldfish are smart for example some will let you pat on their head when they approach you. But you should not put many goldfish in a tank because when they grow up they will need a bigger tank. One goldfish for each variety is enough. Common varieties are Common Fantail, Oranda, Lionhead (it has smaller wen coverage than Oranda, only on top of the head), Black Moor, Calico, Ranchu etc. In my 20-liter tank I once had seven goldfish so the water was very cloudy. Actually 20-liter tank is good for two goldfish only.
f) Single-tail goldfish tank.
g) Tiger Barb, Gold Tiger Barb and Green Tiger Barb (All Puntius tetrazona, the original type with black stripe is hardier) tank.

Fish for cleaned tank and totally new water: Black / White-skirt Tetra. This fish is super hardy. It has sharp eyesight: it darts lightning fast to the water surface to FETCH fish pellet. Other fish do not fetch, but rather just eat the pellet at the water surface.

Fish for level 1 owner from my experience:
1) Platy. It is also called Moon. It may jump out of tank particularly after water change.
2) Long-fin Swordtail. Its hardiness is less than Platy but more than Molly. Due to its hardiness and ability to reproduce in high numbers it has become a nuisance pest as an introduced species in a few countries causing ecological damage.
3) Black Molly (Poecilia sphenops)
4) Common Fantail Goldfish
5) Tiger Barb
6) Dwarf Gourami
7) Bristle-nose Pleco
8) Colorful female Betta
9) Guppy
10) Blood Parrot Cichlid (no scientific name. It is a fish Frankenstein. Some aquarists do not want to keep this)

Fish for level 2:
1) Neon Tetra (Paracheirodon innesi)
2) Black goldfish (some people call it Black Moor)
3) Long-fin Rosy Barb
4) Green Tiger Barb
5) Gold Tiger Barb
6) Sailfin Molly (Poecilia latipinna)
7) Oto (Otocinclus affinus)
8) Gold Chinese Algae Eaters (Gyrinocheilus aymonieri)

Level 3: a) Discus (Symphysodon aequifasciatus)

If you want to have a tank with several types of fish, ensure that
a) the fish are compatible. Do not ask the shopkeeper. They will always say that two fishes are compatible as long as the fishes are not straightforward aggressive (somehow some fish just will not bully other fish when you are present. Smart huh?). Instead watch how the shop puts the fishes or check in the Internet for compatibility.
b) there are only two for each type with unknown gender (except Bristle-nose Pleco should come in one only as there will be not much algae for them) as you do not want your tank to be too crowded. For fish with known gender usually you may want to have 1 male to 2 females (or 2 to 4, or 3 to 5).

If you go to a shop and you see an interesting fish that you do not know its compatibility with other fish but you feel like buying it, do not buy it first. Get the name and check out the compatibility first. You can always go back to the store next time.

Incompatibility examples from my experience:
a) Fancy Guppy, Swordtail, White-skirt Tetra (white version of Black-skirt Tetra) will nibble fancy goldfish's tail.
b) Yellow carp will nibble goldfish's tail until goldfish is killed. Yellow carp looks quite identical with single-tailed goldfish except it leaps and its eyes are further from the mouth (some have whole eye dark in color).
c) Goldfish will eat Neon Tetra and any fish fry / baby  (for example from livebearers).
d) Common Pleco, Chinese Algae Eater and Otto may gasp on Goldfish's side.
e) Dwarf Gourami may starve to death due to imbalanced competition with other fast-swimmers.
f) Albino Red-fin Shark may chase fish that has similar shape and size with it and may gasp on Goldfish’s side.
g) Sailfin Molly and Platy will starve to death if fed with pallet food and kept with Goldfish because they cannot hold the pellet with their mouth.
h) Somehow only one Platy will survive if a group of Platy is kept with Goldfish.

To avoid waste of money buying fish, do NOT mix Goldfish with other fish. It is a rare occasion that other fish is compatible with Goldfish. The temperature need is different too because Goldfish is coldwater fish while tropical fish is from warm-water.

You can keep an Asian Freshwater Clam (Corbicula fluminea) too. It scavenges on the waste in the aquarium.

Fish food
For healthy fish you should have at least two brands of fish food. The food that stays afloat will have less amount of uneaten bit deposited on the substrate. Sinking pellet food is recommended for Goldfish because we do not want the Goldfish to gulp in air during feeding and Goldfish is constantly finding something to eat on the substrate anyway. The smaller the pellet size the better even for big fish like Goldfish because it is easier to digest so the chance of suffering from swim bladder disorder (SBD) is lower. Take a look at the pellet size before paying for the food bag at the shop because the pellet size may vary although the packaging is alike.

Flake food can make the water messy easily but fish that cannot hold pellet food in its mouth and cannot swim fast to chase the pellet in flowing water (for example the Dwarf Gourami) should have flake food.

If you will be away from home, buy food block. The longer you are away, the bigger the block. On the label you can see the number of days the block will take to fully dissolve. Please note that the food block may cloud the water.

You need an auto feeder if you are away from home for more than two weeks.

To have better control of the amount of food you feed in, you can use a tiny plastic coffee spatula. It is small enough to be put inside fish food bag. Some fish foods come with a small spoon.

Tiny plastic coffee spatula

If you keep aquatic invertebrates you should get aquarium iodine. Do not put activated in filter or use foam fractionator (aka protein skimmer - a type of filter) because it will remove trace of iodine. Aquatic invertebrates that are usually kept in the aquarium are shellfish (crustacean and shelled mollusk). An example of crustacean is shrimp. Clam and snail are categorized under shelled mollusk.