Plastic Tanks for Fish Farming: Sizes, Prices and Where to Buy

A plastic tank for fish farming should be a thick-walled virgin HDPE or PP tank, with capacity chosen by species: 50 to 200 liters for small ornamental fish, 300 to 500 liters for Koi and large goldfish, and 1,000 liters or more for food fish such as catfish and tilapia. Farm water needs to stay at pH 6.5 to 8.5 with dissolved oxygen of 4 to 5 mg/l according to FAO material; the location has to be planned ahead, because 1,000 liters of water weigh about 1 ton.

I am Le Van Thang, and I have worked at ICD Vietnam since 2011. The question customers ask most about fish plastic tanks is not the price but “how many liters is enough?” and “is it all right to put it on a rooftop?” This article answers both with real measurements of the 100 liter and 500 liter fish tank models and the square fish tank, together with water thresholds and stocking densities taken from FAO and agricultural extension material, so you can work it out yourself before you buy.

The sections that follow go in turn through why farm in tanks, material, tank shape, capacity and location, the needs of each species such as catfish and Koi, and then how to set up and monitor the water. The last part covers the practical questions we often get on the hotline.

Why choose a plastic tank over a traditional pond tank for fish?

A plastic tank is cheaper than a built tank, installs in a day, can be moved and is easy to drain and clean, so it suits small households, rooftop farming or a trial before investing in a fixed pond or tank.

A cement tank has to be built, left to dry and soaked for several days to leach out lime before fish can go in, and once built it cannot be moved. A plastic tank is bought, rinsed, filled and used; at the end of the season you can drain it, dry it, store it or move it elsewhere. The inner surface is smooth, so dirt sticks poorly and scrubbing is quicker than on a rough cement wall. In return, the small volume of water makes temperature and water quality swing faster than in a pond, so the farmer has to watch more closely, as the technical sections below explain.

Which material is safe for fish?

Material decides the life and safety of the tank. Virgin HDPE is odorless, has a smooth surface that is easy to clean and is flexible, so it rarely cracks under impact; for a tank outdoors, choose one with a UV-stabilizing additive, because polyethylene without UV stability gradually turns brittle in the sun.

Recycled plastic of unknown origin is an option to avoid, especially when raising fish for eating: you do not know what packaging that batch of plastic used to be, it may still carry odor or foreign substances that leach into the water, and it is often brittle and cracks at the corners when carried full of water. Fiberglass composite tanks are rigid and suit large farms in a fixed spot, but they are heavy, hard to move, and their quality depends on the coating on the inner surface. For most needs from 50 to 5,000 liters, a virgin HDPE or PP tank is the best balance of durability, safety and price. ICD Vietnam fish tanks all state virgin PP/HDPE on the product page.

Common types of plastic fish tanks on the market

Fish tanks come in three main types: square or rectangular tanks that use floor area well; round tanks that give an even circulating flow with no dead corners; and small tanks, including clear plastic bins, for ornamental fish you want to watch.

Square and rectangular plastic fish tanks

Square and rectangular tanks are chosen most because they sit against a wall and next to each other without wasting yard corners. One point few people notice is depth: ICD Vietnam’s 200 liter and 300 liter square tanks are both 41 cm tall, wide on top, which suits ornamental fish, fry and young fish that need fast water changes; the 500 liter tank is 77 cm tall, so the water column is deeper and temperature is more stable, which suits food fish and Koi.

Round plastic tanks for fish

A round tank has no corners, so when you aerate or pump water along the wall, the flow circulates evenly around the tank and sediment gathers in the middle of the base where it is easy to draw out. That is why large round tanks such as the 5,000 liter size are often used for catfish and snakehead, species that eat a lot and excrete a lot. The drawback is that it takes more floor area than a square tank of the same capacity and is hard to place side by side.

Special plastic tanks for ornamental fish

For guppies, bettas or small goldfish, a 50 to 100 liter tank on a balcony is enough for a small group. Anyone who wants to watch the fish from the side can choose a small clear bin, but remember that a clear bin lets light through the wall, so algae grows faster. A dark tank, such as dark blue or black, blocks some light, so less algae clings to the wall and the fish color is easier to see from above.

Choosing tank capacity by farming need

Small ornamental fish need 50 to 200 liters, Koi and large goldfish need 300 to 500 liters, and commercial food fish need 1,000 liters or more; the larger the tank, the more stable the temperature and water quality.

• Small scale (guppies, bettas): 50 to 200 liter tanks.
• Medium scale (Koi, large goldfish): 300 to 500 liter tanks, with a filter and an air pump.
• Commercial scale (catfish, snakehead, tilapia): tanks of 1,000 liters or more; large farms use tanks of 2,000 to 5,000 liters.

Capacity also decides the location. Each liter of water weighs about 1 kg, and the whole mass of water presses on the floor right under the tank base. The table below is calculated from the external dimensions on ICD Vietnam product pages (checked on 16 October 2026) and does not include the weight of the tank, filter stones or fish:

Two tanks of nearly equal capacity do not necessarily load the floor equally. The 300 liter tank is low and its base is wider than 1 m², so the load spreads thinner than under the 500 liter tank that is 77 cm tall. If you only have a rooftop, several low tanks placed next to the columns are usually safer than one tall, heavy tank in the middle of the slab.

Practical use for each fish species

Catfish and tilapia tolerate low oxygen, so they are the easiest to keep in a tank; Koi and carp need oxygen-rich water and good filtration; snakehead need a cover because they jump. The tai tuong fish (giant gourami) gulps air from the surface but grows very slowly and must be moved to a bigger tank as it grows; see the guide to raising tai tuong fish in plastic tanks.

Raising Koi in plastic tanks

Koi need clean water, plenty of oxygen and grow fairly fast, so a Koi tank should be 300 to 500 liters or more, preferably with a deep water column. Koi are the same species as common carp, and according to FAO an adult carp needs at least 3 mg/l of dissolved oxygen and ideally 5 mg/l, with a preferred temperature of 23 to 26 °C. So a Koi tank almost always needs an air pump running continuously plus a filter; many keepers add a small tank above as a filter chamber, with water overflowing down to the main tank like a waterfall to filter and add oxygen at the same time.

Raising catfish and tilapia in plastic tanks

These are the two easiest species to keep in a tank, but also the easiest to overstock. A guide to raising catfish in cement tanks from Ninh Binh recommends a density of 30 to 50 fish/m² with a tank depth of 1 to 1.5 m. Plastic tanks are usually shallower than cement tanks (the 500 liter ICD tank is 77 cm tall), so take the low end of that range: for a 500 liter tank with a base of about 0.89 m², stocking about 25 catfish is a sensible start, then adjust to appetite and water quality.

For tilapia, the National Agricultural Extension Center advises stocking 2 to 3 fish/m² in an ordinary pond and 5 to 7 fish/m² in intensive farming with aeration. A plastic tank is a miniature intensive system with little water, so stocking denser than pond levels requires an air pump and frequent water changes. Tilapia prefer warm water of 27 to 30 °C, which suits the southern climate and northern summers.

Oxygen needs of each fish species

Dissolved oxygen (DO) is the figure that decides stocking density and the capacity of the air pump. According to FAO training material on freshwater fish farming, each species has a different minimum, a level to maintain and a preferred temperature:

This table explains why catfish and tilapia are usually chosen when you first farm in tanks: they tolerate moments when the air pump stops or hot weather lowers oxygen. Koi and carp need higher oxygen, so a Koi tank always needs an air pump running continuously or a waterfall filter system as described above. Oxygen in the water is lowest near dawn, so that is also the time to check if you see fish gasping at the surface.

Raising snakehead and small ornamental fish

Snakehead jump a lot, especially when first stocked or when it rains, so a snakehead tank needs a lid or net covering the whole mouth. For guppies and small ornamental fish, adding hornwort or floating plants gives the fish a place to shelter, fry a place to hide, and lets plants absorb some of the waste. For species that need both a water zone and a shallow bank, such as softshell turtles, the tank layout is quite different; see raising softshell turtles in plastic tanks.

What does a plastic tank price quote for fish farming depend on?

The price of a fish tank rises with capacity, wall thickness and type of plastic; ICD Vietnam quotes by model and quantity by hotline and Zalo.

At the same capacity, a tank with a heavier shell usually uses more plastic, has thicker walls and handles impact and water pressure better. Virgin plastic costs more than recycled plastic, and a UV additive also nudges the price up, but these are two things worth paying for if the tank sits outdoors for years. For tanks of 500 liters and up, transport is a significant part of the cost because the goods are bulky, so when you compare prices, compare the price delivered to your site.

Where to buy plastic fish tanks and what to check on delivery?

Buy large fish tanks directly from a manufacturer or a supplier that states the material, dimensions and warranty policy clearly, because tanks of 500 liters and up are bulky and returns are costly if you choose wrong.

ICD Vietnam is a manufacturer and sells fish tanks by model with dimensions on the product page and a 12-month warranty. When a tank arrives, wherever you bought it, check the following before filling it:

• No hairline cracks on the walls and corners, and no white stress marks from knocks in transit.
• An even rim without warping, and even wall thickness when you run a hand around the tank.
• No burnt-plastic smell or odd chemical smell.
• Fill with water for a day in the fixed location, check for leaks and check that the floor below is stable.

Expert-level setup and care of fish in plastic tanks

Four things decide whether fish stay healthy in a tank: treating a new tank, supplying enough oxygen, keeping a stable temperature, and changing water and removing sediment regularly. The order of work when setting up a new tank:

1. Rinse the tank with water, soak it full for one to two days and drain it before stocking fish.
2. Fit an air pump rated for the tank capacity and place the air stone close to the bottom so the bubbles pass through the whole water column.
3. Put the tank under a roof or stretch a shade net so the water does not get too hot at midday.
4. Change part of the water regularly and siphon the bottom sediment; a tank with a bottom drain valve does this much faster.

If you use tap water, let the water stand in the tank for a few days so some chlorine escapes, or use a dechlorinator before stocking. When adding new fish, float the whole bag in the tank for about 15 to 20 minutes so the temperature on both sides equalizes before release.

Water indicators to monitor

The water in a tank is far less than in a pond, so it changes quickly, especially pH and ammonia from fish waste and leftover feed. A drop-type water test kit or test strips let you check weekly against the benchmarks below:

• pH: keep it at 6.5 to 8.5, measured at dawn when pH is lowest in the day.
• Dissolved oxygen: keep to the level for each species in the table above; it is lowest near dawn.
• Ammonia: the lower the better; it rises fast with overfeeding or overstocking.
• Temperature: follow the preferred level for the species, and avoid shallow water in direct midday sun.

Frequently asked questions (FAQ)

Which color of plastic tank is best for fish?

Dark tanks such as deep blue or black suit long-term farming because they block some light, so less algae clings to the wall and the fish color is easy to see from above. White or clear tanks make it easy to watch the fish’s condition and suit quarantine for sick fish or short-term nursery tanks.

Is farming fish in plastic tanks durable?

Yes, if you choose a thick-walled virgin HDPE or PP tank and place it where it is shaded from the sun; a tank outdoors should have a UV additive. ICD Vietnam plastic tanks carry a 12-month warranty under the warranty and repair policy published on the website.

Should I use a used plastic tank to farm fish?

Only when you know for sure what the tank used to hold, ideally clean water or food. Do not use a tank that once held chemicals, oil or pesticides, because residue left in the plastic can leach into the water and kill the fish. An old tank also needs a careful check for cracks at the corners and base before you fill it.

How many catfish can a 500 liter plastic tank hold?

About 25 to start. The Ninh Binh guide to raising catfish in cement tanks recommends 30 to 50 fish/m² with a tank depth of 1 to 1.5 m; the 500 liter ICD tank has a base of about 0.89 m² and is 77 cm tall, shallower than a cement tank, so take the low end and then adjust to appetite and water quality.

How do I buy ICD Vietnam fish tanks?

Contact ICD Vietnam by hotline or Zalo, tell us the fish species, quantity and where the tank will sit, and we will advise a suitable model and quote by quantity. For large tanks, ask about the freight to your address when you receive the quote.

How much does a 1000 liter fish tank weigh when full of water?

About 1 ton of water, plus the weight of the tank, filter stones and fish. So a 1,000 liter tank should sit on the ground or a concrete floor; on a roof slab or balcony it needs a structural engineer’s check, because the design load of a residential balcony under TCVN 2737:2023 is only about 200 kg/m².

Which fish are easiest to raise in a plastic tank?

Catfish and tilapia are the easiest because they tolerate low oxygen: according to FAO, African catfish survive when dissolved oxygen drops to about 1 mg/l thanks to breathing air, and tilapia tolerate 2 mg/l. Among ornamental fish, guppies and goldfish are easy for beginners to care for.

Can I farm fish in a plastic drum?

Yes, with a new HDPE plastic drum or a drum that once held food; a capacity of 200 to 220 liters suits a small number of catfish or tilapia. Do not use a drum that has held chemicals or oil, and cut a wide opening or use an open-top drum to make feeding and cleaning easier.

Contact us for advice on choosing a plastic fish tank

References

• FAO, Simple methods for aquaculture: Management for freshwater fish culture: pH, minimum dissolved oxygen and preferred temperature by species.
• National Agricultural Extension Center, Commercial tilapia farming techniques: pond and intensive stocking densities.
• Ninh Binh Department of Agriculture, Catfish farming model in cement tanks: stocking density and tank depth.
• TCVN 2737:2023 Loads and actions, guidance document from the Institute for Building Science and Technology (IBST): floor loads for apartments and balconies.
• Dimensions, capacity and material of fish tanks: ICD Vietnam product pages, checked on 16 October 2026.