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Common fishes in aquaria and how to care for them


May 9, 2023
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Perth, Australia
Introduction to the articles
There are many popular fish in the aquarium industry. Wherever freshwater or marine, fish have captivated us for many years since the introduction of the glass aquarium in the 1800s. Freshwater fish is the most common type of fish in the hobby, but marine fish are increasingly popular nowadays. But some of the most common of these fish are: Rainbowfish, the danionins, goldfish and bettas.


About the rainbowfishes
Rainbowfishes are one of the fishkeeping hobby's most popular fish because of their colourful and mostly small size. They belong to the family of Melanotaeniidae in the Atherinid order. These include the Australian and New Guinea rainbowfishes, Celebes rainbowfishes and the Madagascan rainbowfishes. Most species are less than 12cm but one species of the Melanotaenia genus reaches up to a length of 20cm.
Madagascan rainbowfishes
Some rainbowfishes live in the island of Madagascar, home to the genus of Bedotia. This genus holds a lot of undescribed species of rainbowfish that have been classified by the IUCN Red List. They are not as popular in the aquarium trade as the Australian and New Guinea rainbowfishes. Their habitats are tannin-stained blackwater with riparian vegetation where the water flow is not too strong. Bedotia madagascariensis and Bedotia geayi is classified as endangered by the IUCN Red List due to habitat loss.
Australian and New Guinea rainbowfishes
The Australian and New Guinea rainbowfishes are the most common seen rainbowfish in the aquarium hobby. They are named that because of the range that the many genuses of the Melanotaeniinae subfamily live in. There are seven genera in the subfamily. Most of the rainbowfishes in the genus Melanotaenia are rare, but some species are common throughout their range. They are found in swamps and streams from Australia and Papua New Guinea. This genus is the most common aquarium rainbowfishes. The Lake Kutubu rainbowfish is an endangered example of the Melanotaenia genus. Pseudomugil is another common genus kept in aquaria. Paska's blue-eye is a critically endangered rainbowfish from this genus. It is only found in the Fly River system in Papua New Guinea.

Celebes rainbowfishes
The Celebes rainbowfishes are a beautiful rainbowfish that some hobbyists keep. There are 5 genera in this subfamily. Telmatherininae is the name of the subfamily that the silversides are in. Nearly all of them are found in the island of Sulawesi in Indonesia, with most of them living in Lakes Matano and Towuti. They are the lesser known rainbowfish because their biology remains somewhat unknown in most of this subfamily.

How to build a rainbowfish community tank
You can use your imagination for this setup. You can do moss and plants, gravel or sand, driftwood or rocks. The livestock must be compatible rainbowfish such as Boeseman's rainbowfish and dwarf rainbowfish, and other similarly compatible fish such as large tetras and catfish. Look for photos sent by other users and watch Youtube videos for reference to your setup. Let the tank cycle. Put the fish in the tank.
How to build a rainbowfish biotope tank
This is the least common setup for rainbowfish, and for more experienced hobbyists. Firstly, extensive research must be done for the biotope you choose (i.e. the Mamberamo River biotope for dwarf rainbowfish), including the pH of that biotope and the tank size of the species of rainbowfish you are looking for. Other native species might live in the rainbowfish's range, so you can add them if you want. Look into Bleher's Biotopes and have a read about rainbowfish biotopes. When you have done some extensive research into the biotope, you can start making the setup. For example, a 136 litre Mamberamo River setup contains river sand mixed in with rainforest litter. Mix the two together and pour a good amount of the mixture in. There are a few native plants in the River including: Nymphaea, Microsorum pteropus, Vallisneria nana and Aponogeton. You can place a large piece of driftwood in the middle of the tank to complete the look. Let the tank cycle and test the water parameters every month to see if everything is okay in the setup. Put the rainbowfishes in the tank.
Rainbowfish care
Many Melanotaeniid rainbowfishes come from alkaline water, so they thrive best between 74° and 78° F at a pH of 7.0 to 8.0 and alkalinity between 5 and 20 dKH. Bedotiinid rainbowfishes come from more acidic water and should be kept between 74° and 80°F with a pH of 6.5 to 7.5 and alkalinity between 3 and 14 dKH. Pseudomugilid rainbowfishes also come from acidic water and must be kept between 76° and 82° F and at a pH of 6.5 to 7.5 and alkalinity between 5 and 10 dKH. The tank size depends on the species of rainbowfish you are caring for; for the blue-eyes 10 gallons is required for a small group, some can be kept in a 20 gallon tank, and many can be kept at 30 gallons or more for larger rainbowfishes. Rainbowfishes are omnivores, they eat vegetables and frozen/live foods such as bloodworms and brine shrimp, but flakes must be the staple diet. Always feed them a small amount of food once or twice a day. 30% water changes are ideal for a rainbowfish-only aquarium. Their lifespan are between 5 to 8 years, depending on the species. Some rainbowfishes can carry a disease that is not curable called fish tuberculosis (FTB). It affects captive rainbowfish. It's a major issue for the world and Australia. Buy wild caught ones to prevent FTB.

A recap of the article:
  1. There are four main subfamilies of rainbowfishes: Melanotaeniinae, Bedotiinae, Psudeomungilinae and Telmatherininae.
  2. Australian and New Guinea rainbowfishes are the most common rainbowfish in the aquarium trade.
  3. Madagascan rainbowfishes are rarer in the hobby because of specific care needs i.e. acidic water.
  4. Celebes rainbowfishes are native to Sulawesi.
  5. There are two different tank types for rainbowfish lovers to build, the biotope and the community tank.
  6. There is a disease for wild-caught rainbowfish called fish tuberculosis
  7. Care depends on the type of rainbowfish you are looking for.
Rainbowfishes are a true gem in the hobby and can be great community fish, if you care for them properly. Although there is a rare fish disease for them, the rainbowfish will mostly survive through tank-bred populations and some wild-caught fish. Other than that, these smaller rainbowfish are great for beginners and larger ones for more advanced hobbyists. Their beautiful colours are an attention-grabber for anyone who sees them. These fish are great to keep for many years to come.


About the danionins
The danionins that live in South and South-east Asia. There are 38 genera in total that goes into Danioinae, including the Rasbora, Danio, Devario and Microdevario genera. The danionins are a diverse group that are mostly very colourful, including the pearl danio and the Espei rasbora. Danio species often have barbels and horizontal stripes or spots, while Devario species mostly have vertical or horizontal stripes and rudimentary barbels. The rasboras have different colour patterns depending on the species. Most danionins are popular aquarium fish because of their colourful bodies and striking patterns.

There are 12 genera on the Rasbora family, the most notable of these are Microdevario, Rasbora and Trigonostigma. These danionins are small fish, usually reaching less than 10cm in length. They too are popular aquarium fish because of their small size and colourful bodies. Their bodies are usually plump and the females are usually look fatter than the males. Some of the smallest rasboras that live in Thailand and Myanmar is Microdevario kubotai. This 2cm fish lives in the Ataran basin and the Suriya River in both (Myanmar for Ataran and Thailand for the Suriya) countries respectively. They are popular to the aquarium trade because of their unique green colour all over their bodies. They are classified as Least Concern by the IUCN Red List.

Danio and Devario
The most common genus of the two is the Danio genus. These fish are similar to the Devario despite having barbels present on their face. The most well known member of the Danio genus is the zebrafish. This 5cm fish is used extensively for science research on drugs, and disease, among others. They are a great freshwater fish for a beginner or novice aquarist. The Devario genus is similar to the Danio genus, but have horizontal or vertical bars, like Danios have, but some have spots on their bodies. The Lake Inle Danio is an endangered example of the Devario genus. This fish is rare due to the water hycanith in some areas of the Lake and habitat loss. This fish reaches to a size of 10cm.

How to build a danionin tank
There are two types of tanks for Danionins: Community and Biotope. The community tank is for beginners, but the biotope tank is for the more experienced aquarist. For the community tank, you can use your imagination, add the substrate you want, arrange some different compatible plants for the fish to feel safe and add some hardscape (rocks and wood). Fill the tank and let it cycle. Add some compatible peaceful danionins to the tank. For the biotope, do some research for the natural habitat where the danionin lives. These fish will thrive more than in a community tank if you build a biotope aquarium for a certain species of danionin. For example, you may want to build a softwater biotope for Microdevario kubotai. These rasboras live in schools in 20 or more in the wild. You may want to build the biotope in a 130 litre tank, which is big enough for a large school of these small fish. You will need river sand, rocks and some native plants for the Suriya River biotope. Construct the biotope with these materials, and choose plants that are native to their area. After you have filled the tank and let it cycle, add the Kubotai rasboras and other livestock that are native to their area (i.e. Akysis vespa).

Danionin care
Danionins are easy fish to take care if you look after them properly. For danios the pH should be between 7.0 and 7.8, alkalinity between 3° and 8° dkH (50 ppm to 140 ppm) and temperature between 70° and 78°F. If the aquarium is kept in rooms below 70° a heater is required. For rasboras the pH should be between 6.8 and 7.8, alkalinity between 3° and 8° dkH (50 ppm to 140 ppm), and temperature between 75° and 80°F. Wild-caught fish prefer a pH of 5.0 to 7.0 and KH between 1°and 3° (20 ppm to 50 ppm). These fish will need a 10-30% water change, depending on the species you want to care. The tank size for smaller danionins are 10-20 gallons, while larger ones will have a tank size of 35 gallons or more. Danionins are omnivores, so they eat plant and meat matter.

A recap on the article:
  1. There are 38 genera on the Danioinae subfamily, including 12 for the rasboras.
  2. There are some difference between the main 3 genera
  3. These fish are popular to the aquarium trade because of their colours and patterns
  4. Different care requirements are for different danionin species.
These fish are very easy to keep in the aquarium because of their peaceful temperament and schooling behaviour. However you must keep them in 10 gallons or more. These fish are a joy to keep for kids and adults alike.


About goldfish
The common goldfish is a species of carp originated in China thousands of years ago. This fish is popular for the old and the young because of its somewhat small size during the first few months. However these fish can get MASSIVE over time until they die. There are a lot of fancy goldfish varieties, which most of the smaller ones are very good for intermediate aquarists. This species is one of the first fish to become popular in the early aquarium hobby.

How to build a goldfish tank
You MUST need a large tank (3ft or more if your planning to have more goldfish) for this build for two goldfish, because in Rome it is illegal to keep only one goldfish or keep them in a bowl. Goldfish-friendly gravel is required and so are plants that withstand bite marks. Anubias and Java fern are two examples of goldfish-friendly plants. You will need some large rocks or driftwood for the hardscape of the build. Add the plants last. Fill the tank and let it cycle. Add the fish in.
Goldfish care
These fish are somewhat hard to care for in their entire life, compared to rainbowfish and the danionins. Goldfish have a long lifespan, so you better need a very large tank to start with because some varieties can grow very large (a foot long). These fish need a filter that cleans up their large amount of waste. The optimum temperature for fancy goldfish is 68° to 74°F, while comets and shubunkins should be kept between 60° and 70°F. pH is not critical, but ideally should be between 7.0 and 8.4. Rapid changes in temperature or water chemistry can be harmful, if not fatal to goldfish. A tablespoon of aquarium or sea salt per 5 gallons can also be used to help keep goldfish in good health. Goldfish are omnivores, not herbivores, as told in a myth by kids and old fish keepers. They enjoy live and frozen foods such as bloodworms and brine shrimp. They need a water change of 40-50% every fortnight to keep them healthy and happy. They should NOT be kept in bowls or small aquaria.

A recap of the article:
  1. Goldfish originated in China thousands of years ago
  2. They grow very big in some varieties
  3. Goldfish are harder to care than other fish, this will be easier if you care for them correctly
  4. Goldfish don't belong in bowls or small aquaria
These fish are loved by the aquarium hobby for a long time, but don't be fooled by their problematic waste issues and bloating. If you care for them properly, they will live for a decade or 3 decades, even living as long as an old fish owner. Goldfish are better off being a pond fish than an aquarium fish for a good reason.


About Bettas
Betta is the name of the genus of gourami-like fish that live in South-east Asia in the wild. These fish, especially domestic bettas, are very common in the aquarium hobby, and you know why. The domestics are very colourful, while the wild type bettas have slightly less colours. They, like goldfish, are loved by the hobby because of their hardiness and their tails. There are 73 species in the Betta genus. Domestics are more aggressive than wild bettas because they were bred to fight. Bettas are air breathers, so they have a special organ called the labyrinth organ to help them breathe atmospheric air.

Wild bettas
Wild bettas make up most of the Betta genus. Some wild bettas can be seen in the aquarium trade. Most of them are rare because of threats that affect their future. The Krabi mouthbrooding betta is critically endangered because of habitat loss and agriculture near vital habitat. Some bettas are mouthbrooders, and some are egg layers. Experienced aquarists oftentimes try to save these species from extinction by breeding them.
How to build a betta tank
A betta tank must have the following: The correct substrate, hardscape and compatible plants. It must be 5-10 gallons or more. For domestics you can use your imagination to build your own betta tank. Watch YouTube videos for inspiration for your build. Making your domestic betta tank a blackwater aquarium is optional. Fill the tank and let it cycle. Put your betta in after a few weeks of cycling. For wild bettas, they need to live in blackwater environments. You will need botanicals for the setup. You will need some plants that live in blackwater setups as well. River sand or gravel will be the substrate for a wild betta tank. Like the domestic betta tank, it must be 5-10 gallons or more, depending on the species of wild betta you are looking for. Fill the tank and let it cycle for a few weeks. Introduce the domestic or wild betta in the tank.

Betta care
For domestic bettas, care is simple. They prefer calm water with a pH between 6.8 and 7.5. While they may seem to tolerate cooler temperatures, they will be inactive and more susceptible to disease, therefore it’s best for their overall health to keep the temperature between 76° and 85°F. Wild bettas are slightly more difficult to care than domestics. They can be kept on a pH between and 7.5. If the tank water is kept clean, catappa leaves, twigs and alder cones, and a lot of plants are added, wild betta fish will do fine. The water temperature should be between 72 and 80°F. Bettas should NOT be kept in bowls, vases or aquaria that are too small for them (less than 5-10 gallons). The tank should not have two domestic males in the same tank because one or both die after a big fight. Bettas prefer small water changes of 10-20% every week to keep them healthy. Bettas are carnivores, while they may accept pellets, they prefer live or frozen foods as an occasional reward.

A recap of the article:
  1. The Betta genus contains 73 species
  2. Domestics are more hardier than wild bettas
  3. They should not be kept in bowls, vases or aquaria that are too small for them
Bettas are fairly easy to look after because of their pretty colours and hardiness in the aquarium hobby. They are one of the best fish for beginners, therefore the reasons why these fish are so loved by the aquarium hobby. Their wild, eye-catching coloring has made them one of the most popular fish in the aquarium hobby and a lot of misinformation is available online. However it’s easy to be misled if you are a beginner.

Conclusion to the articles
These four fish are easy to care if you look after them properly and do your research. Their popularity in the hobby inspired many novice aquarists to start their career in fishkeeping. Even though there are misinformation and myths that happen in the hobby, the odds of caring them well depends on the aquarist. Some of these fish help them be more confident on the species they choose to care.
Happy fishkeeping!
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