Bitterling Care Guide: Diet, Tank Mates, Diseases, Breeding & More

Updated: December 17, 2022

Bitterlings are a very small freshwater fish that are native to parts of Asia.

They’re not the most popular fish in the hobby, but they’re definitely unique and interesting little creatures.

But before you go out and get one (or a few), there are a few things you need to know about their care.

In this guide, we’ll teach you everything you need to know about Bitterling care. You’ll learn about their diet, tank mates, habitat, and more!

Species overview

The Bitterling (Acheilognathus longipinnis) is a species of freshwater fish that is native to East Asia. It can be found in China, Japan, and Korea.

This fish prefers slow-moving waters with a lot of vegetation. This could be anything from a river or stream to a pond or lake.

They are very small fish, only growing to be about 2 inches in length. Despite their small size, they are very active and are constantly moving around the tank.

Bitterlings are omnivores and will eat a variety of different foods. In the wild, their diet consists of small insects, crustaceans, and zooplankton.

Bitterlings are a popular choice for aquariums because of their small size and active nature. They are also easy to care for and are very compatible with a wide variety of tank mates.



The Bitterling is a small and delicate freshwater fish. They have a long and slender body shape that is typical of many cyprinids.

The coloration on this fish is relatively subdued compared to other freshwater species. They are mostly a pale brown with a few darker spots on their sides. The fins on this fish are also a pale brown color.

The dorsal fin on this fish is located towards the back of their body and is relatively short. The anal fin is located towards the back of the fish as well and is also quite short.

The caudal fin on this fish is forked and relatively large compared to the rest of their body.

The most distinctive feature of this fish is the long and thin tube that extends from their mouth. This is used to breathe in water and extract oxygen from it.


The average lifespan of a Bitterling is 3 to 5 years. There are a number of factors that impact their life expectancy.

For starters. if these fish haven’t reproduced then their lifespan will usually be on the higher side of this range. That process can really take a toll on the fish.

The general level of care they receive obviously matters a great deal as well. Even though these are very hardy fish, they’ll obviously live longer in optimal conditions.


The maximum size of a Bitterling is about 2 inches in length when fully grown. It’s not uncommon for these fish to stop growing at 1 inch depending on their level of care and genetic factors.


Tank Size

The recommended tank size for bitterling is 5 to 10 gallons. If you’re planning on keeping multiple fish, you should add an additional gallon for each fish.

Water Parameters

Bitterlings are a bit more delicate than other freshwater fish so it’s important to maintain consistent water parameters. This species is also a bit more sensitive to water changes so be sure to acclimate them slowly.

The following water parameters are ideal for bitterling care.

  • Water temperature: 60 to 68 degrees Fahrenheit
  • pH levels: 6.0 to 7.5
  • Water hardness: 2 to 12 dGH
  • Alkalinity Levels: 4-8 dKH

What To Put In Their Tank

Bitterlings are easy to keep and don’t really have any strict requirements when it comes to setting up their tank.

We recommend a fairly standard setup with some plants, rocks, and driftwood. These fish like to have some places to hide, so make sure there are plenty of nooks and crannies for them to explore.

The substrate can be anything you want. Bitterlings aren’t known to be diggers so gravel or sand will work just fine.

As for plants, anything that can tolerate the water conditions will do. Hornwort, water wisteria, and java moss are all great choices.

You shouldn’t need to add anything else to their tank. Bitterlings are peaceful fish that don’t need any special accommodations.

Common Diseases

Bitterlings are actually quite hardy and don’t fall ill very often. However, that doesn’t mean that they’re immune to disease.

There are a few illnesses that these fish are susceptible to, the most common being ich.

Ich is a very common freshwater fish disease that is caused by a parasites. It’s easily recognizable as it presents itself as white spots on the body of the fish.

While ich is the most common disease that bitterlings experience, there are a few others that can affect them as well.

Some other potential diseases include bacterial infections, fungal infections, and parasites.

As with any other fish, the best way to keep your bitterling healthy is to maintain a clean and stable tank. This will help to prevent the spread of disease and will also make your fish less likely to fall ill in the first place.

Behavior & Temperament

Bitterlings are very shy fish. They like to stay hidden away in plants and other aquarium décor. When they first arrive in a new environment, they’ll likely spend all their time hiding.

It may take a little while, but eventually, they’ll become more comfortable and start to come out more. They’ll still hide when they’re startled, but they won’t spend their entire time in hiding.

Bitterlings are also peaceful fish. They generally don’t bother other creatures in the tank and mind their own business. The only time they may become aggressive is during mating season.

During this time, males can become territorial and may fight with each other for the chance to mate. If you’re keeping multiple males in the same tank, you may need to remove the weaker ones to avoid any serious injuries.

Tank Mates

Bitterlings are a unique species of fish that come with a few challenges. The biggest one is finding appropriate tank mates.

First, these fish are quite small. They only grow to be about 2 inches in length. This puts them at a disadvantage when it comes to finding tank mates.

Most fish that can tolerate their water conditions are too large and will see them as food. This is why it’s important to find smaller fish that can coexist peacefully.

Bitterlings are also rather delicate. They’re not the hardiest of fish and can be sensitive to changes in water quality. As a result, you’ll need to find tank mates that are low-maintenance and not too active.

With all of that in mind, here are some potential tank mates for bitterlings:


Bitterlings are a little more difficult to breed in captivity since they require a specific host fish to lay their eggs in. The most common host fish in captivity is the Japanese rice fish or medaka.

First, you’ll need to set up a breeding tank. It should be at least 10 gallons and filled with soft, acidic water. Then, add some live plants and a few pieces of driftwood to help create hiding places.

Next, you’ll need to add your medaka fish. The ratio should be two females for every male. Once they’re in the tank, feed them a diet of live foods and high-quality pellets.

When the fish are ready to spawn, the female will lay her eggs in the gills of the medaka. The male will then fertilize them. This process usually takes place at night.

Once the eggs are laid, remove the medaka from the tank. The bitterlings will take care of the eggs from there.

After about two weeks, the eggs will hatch. At that point, you can start feeding the fry live foods like brine shrimp and daphnia.


The Bitterling is a great fish for beginner aquarists. They’re very easy to care for and are very peaceful, making them a great addition to community tanks.

Although they’re a small fish, they’re very active and have a lot of personality. We think they’re a great option for people who are looking for something a little different than the standard community fish.

If you’re looking for a new fish to add to your tank, we highly recommend the Bitterling!