Beginner's Guide

Small Tropical Fish That Does Not Require Much Space

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Aquariums have been around for 100 years. From small glass pots to huge containers with tons of accessories, we all have our way of keeping them. 

There are various fish available today either in pure form or crossbred in captivity, just for the pleasure of our eyes. Fish can be categorized into multiple types regarding how they breed, what kind of water they need, their size, temperament, level of care they need, and so on.

It is a fact that some fish just love warm water. They thrive particularly only in warm water. Such types of fish are called tropical fish. To provide warmth in the tank, heaters of different capacities are used according to the size of an aquarium. Aquarium heaters are designed in such a way that they maintain the warmth in the tank. 

The tropical fish varies from size. Platinum Arowana is the most expensive and one of the biggest aquarium fish, and it is tropical. But we are not going to discuss such fish today, are we? As the title suggests, we will be looking at some small tropical fish that don’t require much space. 

In this section, I have discussed the most common small tropical fish that doesn’t require much space. I have mentioned their origin, the minimum tank size, and the breeding tank size. I have also included whether keeping the fish in a bowl is a good option or not.  

List of Low Maintenance Small Tropical Fish That Does not Require Much of Space

If you cannot afford a 5-10 gallon tank I am sorry, fish keeping is not for you. In the section below, I have enlisted some fish that can do well in a 5-10 gallon tank and are very easy for beginners to care for. These fishes were small, hardy, and tropical are the first option for beginners.  

Platy (Xiphophorus maculatus)

Rainbow Wag Platy

These fish originate from the eastern coast of Central America and southern Mexico. Platy are very hardy fish and a perfect match for beginners. You can enjoy their active, joyful, and colorful nature better if the tank is maintained correctly. 

How much space do they need?

The maximum size that platies can grow up to is 3 inches. A school of 5-6 fish needs at least 10 gallons of water. This is because platies are incredibly active and like to move around either for mating or just for fun.

Always keep the female to male ratio at 1:2.

But in a 10 gallons tank, it is suitable to keep only males because keeping males and females in a small container can lead to overcrowding because of the continuous breeding cycle.

Caring your platy

They prefer a water pH of 6.8-8.5. The water should be less acidic and can be slightly basic or alkaline. 

The temperature range is also huge, ranging from 72-82 F. This huge range in pH and temperature shows their adapting capability in various environments. 

Platy fish mostly prefer hard water but can also survive in slightly soft water. The recommended hardness is about 10-28 dGH. 

Keeping platies in a bowl is not a good option because you must change water frequently as you can’t install a filter. This causes stress to the fish. Also, platies tend to live in a group, and in a bowl, you may have to keep them alone due to insufficient size. 

Harlequin Rasbora (Trigonostigma heteromorpha)

Harlequin Rasbora fish originate from parts of southeast Asia. They can be commonly seen around Malaysia, Singapore, and Thailand. 

Although native to the soft inland water system, they can be found all over the world due to their amazing adapting capability. 

They are shoaling fish, which means that they prefer to live in a group of the same species. If you have a tank of around 10 gallons size, you can keep 8-10 rasboras easily in them. 

How much space do they need?

They can grow up to a maximum size of 1.5 inches. The minimum tank size would be 10 gallons. So, in a 10 gallons tank, around 8-10 rasboras can live pretty comfortably. A tank size less than that, however, can get pretty tight for the same number of fishes. Now for every two gallons you increase, one fish can be added. 

Be sure to have an alternate tank or breeding tanks because they are fast breeders, and within months the number of fish will be doubled. A 10-gallon tank is certainly not going to be enough.  

Caring your Harlequin Rasbora

Rasboras prefer a temperature of about 70-82 F. A pH of rang 5.5 to 7 is perfect for them to thrive. 

You must minimize the hardness as much as you can and kept at around 1-10 dGH or dKH. These fish also prefer live plants around them. 

And like always, don’t get a fishbowl and dump your fish in a bowl. They are made for decorative items, not for your fish.

Guppies (Poecilia reticulata) 

Guppy Fish Care

Guppies originate from the north-east of Southern America. They are one of the most widely distributed freshwater fish in the world. 

If you have been a fish keeper for a long time, then you must have encountered them one way or the other. They are hardy fish and adapt amazingly even in harsh conditions. 

How much space do they need?

The males are smaller and can grow up to about 1.4 inches, whereas the female can grow up to 2.4 inches. 

In a small tank, there are two rules you need to follow. The first rule is not to keep alternate sexes because they will reproduce, and you do not want that in a small tank. The second rule is that you must have a gallon of water for every inch of fish. So, in a five-gallon container, you can have two females or 3-4 males. In a ten-gallon tank, three females and two males will be perfect. 

For more ideas on how much space do Guppies need, read our article on “How many Guppies in a 20-gallon Tank?”

Caring your Guppies

They prefer a tank temperature of 23–25 °C (73-77 °F). The preferred pH ranges from 6.8 to 7.8. They thrive in a hardness of about 8-12 dGH. They handle the planted aquarium very well. 

You can also keep guppy in a bowl, but I or any fish lover won’t recommend that. This will give stress to the fish, and it will not live long because of its grouping nature.

Guppies have been classified as both schooling and shoaling fish as they show both properties depending upon the situation.

I recommend you read our article on “Guppy Disease and Treatment” to get more knowledge on how to take care of your Guppies.

Mollies (Poecilia sphenops)

Molly fish fry

Mollies originate from the freshwater rivers and salty waters from Mexico. After guppies, they are the most widely distributed tropical live bearing fish. 

We can generally find molly fish in freshwater, but in rare cases, you can spot them in salty water but in small groups. Mollies are incredibly hardy and easy to care for. They remain small their entire life and are very peaceful. 

How much space do they need?

Mollies also exhibit sexual dimorphism as a male can grow up to 3.2 inches and female up to 4.8 inches. Because of this, you should consider a minimum of a 10-gallon tank for a group of 2 to 3 mollies at most. 

Again, you should not alternate the sexes because they reproduce quite frequently. If you want to mate them, you can use a separate mating tank and can raise the fry there. 

Note that 10 gallons are the minimum space they need. Less than that causes stress and less space for them to swim. 

Caring your mollies

By keeping the tank temperature at 70-85⁰ Fahrenheit, you can make them feel like they are in their natural habitat. 

This fish also prefers hard water (15-30 dGH) and prefers a higher water pH, mostly 8.0. The preferable pH value of the water differs for different types of mollies, but the values from 7.5 to 8.5 are always suitable. I don’t recommend overcrowding. You must provide plenty of plants for hiding.

Putting mollies in a bowl might be the last thing that you should do. A bowl doesn’t provide the necessary circulation and filtration that mollies need. But if you have a 10-gallon bowl, then you are good to go, but it should be clean and heated correctly. 

Neon tetra (Paracheirodon innesi)

Neon Tetra Fish Care | Paracheirodon innesi

Neon tetras are found in the north-west part of the Amazon basin around Colombia, Brazil, and Peru. They are found in blackwater streams and sometimes can also be found in clearwater streams. 

Due to its vibrant colors and hardy nature, it is famous worldwide as an ideal fish for beginners. 

How much space do they need?

Neon tetras grow up to 3.5 cm. The tank size for a minimum of 15 neon tetras is 20 gallons. Most aquarists will recommend a school of 10-15 tetras. 

In a 10-gallon tank, you can have ten neon tetras. You can also keep them in a 5-gallon tank, but in this tank, you can only keep about 5-6 same-sexed tetras, and this is not the ideal school size. So, a minimum tank considering a proper school size will be 10 gallons.

Caring your neon tetras

They prefer a tank with a water temperature 70-81 F. 

The pH should be at around 6-7. They prefer slightly acidic water but loathe even slight alkalinity in water. 

Also, the water must be soft with less than ten dGH of hardness. Neon tetras can also live well with plants of all kinds. 

You can also keep them in a bowl if you have a proper heater and filter system. In a bowl, three neon tetras of the same sex will do good. 

But note that keeping any fish in a small bowl is not suitable for fish, so always prioritize a tank. 

Dwarf gourami (Trichogaster lalius)

Dwarf Gourami

The dwarf Gouramis originate from South Asia’s freshwater lakes and slow-moving streams. 

These fish are labyrinth fish, which means that they have poorly developed gills and need breathing assistance from a labyrinth organ and must have access to the surface of the water.

How much space do they need?

They can reach a length of about 3.5 inches. This is perfect for even small aquariums, but I don’t recommend putting them in something smaller than 10 gallons. 

Regarding their size, only three dwarf gouramis can be placed in a ten-gallon tank that too of the same sex. If you want to go higher, then add 3 gallons of water for each added gouramis. 

Twenty gallons is the minimum size if you want them to mate. For every male you have, there must be at least two females.

Caring your dwarf gouramis

In the wild, it experiences soft, acidic water and expects similar conditions in the aquarium. 

Generally, temperature between 72F and 82F is suitable for it to thrive. 

A pH of 6 to 7.5 is adequate. A water hardness between 3-12 dGH/dKH is perfect. 

If you have a bowl with less than 5 gallons capacity, then you should strictly avoid placing gouramis into it. 

Considering their size and their social behavior, a 10-gallon tank is a minimum choice for them. 

Zebra Danios (Danio rerio)

Zebra Danio

They originate from different parts of central Asia like Nepal, Bangladesh, India, Myanmar, etc. You can find them in fast-flowing rivers, so they don’t mind a high current level in the aquarium. They are hardy and a good choice for beginners. 

Zebra Danios are schooling fish, and I recommend a minimum of 6 fish for a tank of at least 10 gallons. They are among the most active swimmers among aquarium fish, and the tank consisting of danios is never dull.

How much space do they need?

An adult danio can grow up to 2 inches maximum. Due to this small size, they can live in a small 5-gallon tank. 

But due to their hyperactive and social nature, a bigger tank is perfect for them to thrive. Consider a tank of 10 gallons capacity to be minimum for them, but in this tank, you should keep only 5-6 fishes. 

For every one fish you add, you must increase 2 gallons size. If you have a good budget and space, then I would recommend getting a 20-gallon tank and filling it with 10-12 danios with a little water flow.   

Caring your zebra danios

Although regarded as tropical fish, they can survive easily at low temperatures as 60 F. However; experts recommend a temperature between 64F to 74F. 

They prefer slightly acidic water, so a pH of 6.5 to 7 is suitable. For them to thrive, a hardness of 5 to 12 dGH is mandatory. 

They love fast-flowing current, so you can install a moderate to high current in the tank. 

You should not place the danios in a bowl at any cost. They are small fish, so you might think that they can survive in a small space, but that is not true. They are active fish and need a lot of swimming space which a bowl surely can’t offer. 

Consider reading our article on “Danio Fish Disease and Treatment” to get more knowledge on how to take care of your Guppies.

Betta (Betta splendens)

Betta Splendens

One of the most beautiful fish among fish keepers. These fish originate from Southeast Asia, Thailand, to be precise. They are also the national fish of Thailand. 

Bettas are believed to be super aggressive and also show dominant behavior in the tank over other fishes. However, with the right tank mates, they can be friendly. They are neither easy nor hard to care for. 

How much space do they need?

Bettas can get up to 2.25 inches long. Bettas are usually kept alone in a small tank. They breathe through the labyrinth organ, so small oxygen concentration in the water doesn’t affect them. 

In stores, you can see them being kept in small cups. However, this is not the ideal size. The minimum tank size for a betta would be a 5-Gallon tank. The more, the merrier is not the case with bettas because they like to live alone and show territorial behavior in groups. 

Keeping a single betta in a 10-gallon tank would be unnecessary. The ideal way of keeping betta is in a 5-Gallon tank, alone.  

Males should not be kept together at any cost. Males and females must only be kept together while breeding them.  

For detail information on Betta Tank Setup, Read our article on “How to Setup a Betta Tank.”

Caring your Betta

The water must be kept warm at around 75-80 F. The water pH must be around 6-8. Hardness can be of the huge range of 5-36 dGH. 

Betta needs filters all the time. They have a labyrinth organ for respiration. So, the air pump is mandatory. However, you must add a good quality aquarium filter.

Betta fish looks great in a planted tank of, if possible, add some live plants to your tank.

Most of the betta sold end up in a fishbowl. This is the cruelest thing you can ever do to a poor little soul. 

Though betta fish can live in a small area, they do require free space to swim freely. You cannot add aquarium equipment in a bowl, can you? 

A fishbowl and a 5-gallon tank cost the same, so why to keep them I a bowl? Get a tank else don’t pet a betta fish.

Pea puffer (Carinotetraodon travancoricus)

It is an endangered species and probably the smallest pufferfish. It is a freshwater species that originate from southwest India. Although you can sometimes find them in slightly brackish(salty) water, you mustn’t place them in salty conditions in the tank. They are territorial and also highly aggressive. They prefer a heavily planted aquarium.

How much space do they need?

The maximum length that the pea puffer reach is 1.4 inches. Although they are quite tiny fish, the minimum size for one pea puffer is 5 gallons. For every added pea puffer, you must increase the size by 5 gallons. A breeding tank, however, must be of 20 gallons so that it can host the fries as well. In a breeding tank, there should be three females and a male. 

In a 10-gallon tank, you should place two males or two females to prevent breeding that may cause overpopulation.  

Caring your pea puffer 

They prefer a water temperature of about 77-90 F. A pH ranging from 6.5 to 8.5 is perfect for them to thrive in. You should keep the water flow minimum. The total hardness of water must be around 125 ppm or 7.5 dGH. You must densely plant their tank.  

Keeping a pea puffer in a bowl shouldn’t be done at any cost. Pea Puffe is an active fish and needs a lot of swimming space, so you should avoid anything less than 5 gallons. 

Paradise gourami (Macropodus opercularis)

Paradise Gourami

These fish are considered by many as the first fish of tropical fish-keeping hobby. In terms of history, the only fish that comes close is goldfish. This fish is certainly among the most beautiful fish in the aquarium hobby. It originates from parts of southeast Asia like China, Japan, Hongkong, Taiwan, and Malaysia. People get attracted to these by their vibrant colors at first but later end up avoiding them due to their aggressive nature.

How much space do they need?

Dwarf Gouramis measure up to 4 inches in length. So, a 10-gallon tank would be minimum tank size. In this tank, you can place two gouramis of the same sexes. They are also good community fish so you can keep just one with another schooling group like five neon tetras. 

A breeding tank, however, should be larger in size, i.e., about 20 inches minimum. Here you can keep two females and a male. You should moderately plant the aquarium with lots of hiding spots.   

Caring your paradise gouramis 

You must use heaters to maintain a warm temperature of about 70-82 F. The water can be slightly acidic or basic, but we must avoid extremes. You must maintain a pH of about 6-8. Hardness should be about 5-30 dGH.  

Keeping dwarf gouramis in a bowl is not advisable. They are community fish and socially active. They prefer being around other fish so, placing them alone in a bowl is the worst thing you can do for them. 

Read the article on “Gouramis Diseases and Treatment” for more info on how to care for Gouramis.

Scarlet Badis (Dario dario)

Scarlet Badis

Scarlet Badis are among the smallest tropical freshwater fish that are available today. 

They are categorized as nano-fish due to their small size. Scarlet Badis originate from the Brahmaputra River in India. It inhabits shallow and clear water with lots of aquatic vegetation. 

How much space do they need?

Males tend to grow about 0.71 inches, whereas females grow only up to 0.51 inches. The minimum tank size for scarlet Badis is a 5-Gallon tank. In this tank, you should keep only one male and about 2 to 3 females.

If you want to keep more than a male, then increase 1 gallon for each male. The male Scarlet Badis should always be kept in a bigger tank because they are territorial and tend to establish their territory inside the tank. 

You can easily keep two males and 4-5 females in a 10-gallon tank. But the container should be densely planted so the males can establish their territory properly.

Caring your Scarlet Badis

Keeping the temperature at about 71-79 F would recreate their natural habitat. pH should range from 6.5 to 7.5. The hardness should be 10-20 dGH. The water movement must be slow, and you should densely plant the tank. 

You can also keep them in a bowl of not less than 5 gallons capacity as long as you don’t place two or more males together, and you heavily plant the bowl. In a bowl, you can keep a male and a female, but you should keep another tank ready because they will mate, and a bowl is not enough for the fries.  


So, tropical means hardy (not literally). Yes, small tropical fishes are very easy to care for, at least the ones that I have mentioned above. But there are various tropical fish that you should avoid keeping if you are a beginner like discus and stingray. If you are a beginner, then buy a heater, a filter, and follow my fish profile above for tropical fish. Note that you must always start with something easy. This boosts your confidence and encourages you to continue your hobby of fish-keeping. 

If done rightly, tropical fish can get easier than fresh-cold-water fish. So, I recommend you to start with small tropical fish that are hardy and move onto something more significant. I think I have discussed everything regarding the small tropical fish that does not require much space in your aquarium.

I hope you enjoyed the article.

Thank you. 


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