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Japanese Rice Fish – Care, Feeding, Breeding, Requirements & Tank Mates

The Japanese rice fish (Oryzias Latipes) are one of the most popular pet fish that people have raised in aquariums for a long time. They are also known as the Medaka or the Japanese killifish. They come from They are very small in size and are famous for their beautiful colors.

They are characterized by their semi-transparent orange or gold color and some of them have blue eyes. The Japanese citizens have been raising them in aquariums since the seventeenth century.

After that, they have spread to Korea, Vietnam, India and Pakistan. The Japanese rice fish have an elongated body, and the back has a slight resemblance of an arch.

One of the characteristics that make them very beautiful is that their bodies glow in the dark. The most famous kinds of the Japanese rice fish are the gold and moonlight medaka. The gold medaka existed since ancient times, whereas the moonlight medaka are a new bred color morph.

Naturally, the Japanese rice fish live in the rice paddies of Japan. This is the ideal place for fish under the “Oryzias” genus. The main reason is the inexistence of predators. Another reason is that the water temperature is suitable for them.

Recently, scientists used these fish in experiments for biological development. A group of medaka was sent to outer space, as some scientists believe that they can breed faster and easier there.

Raising and housing these fish is easy, but they require a special environment to live in. Here, we will get to know everything about these magnificent creatures.

Also, we will be discussing all the requirements starting from the aquarium and all the way to the possible diseases.

Rice Fish Aquarium Requirements

Rice Fish Aquarium Requirements

Rice Fish Aquarium Requirements

The Japanese rice fish live in groups. These groups are referred to as schools. Despite this fact, sometimes they tend to move on their own or in pairs. The Japanese rice paddies are the natural habitat for these fish.

So, basically you need to create a replica of this environment. Due to their small size, they don’t really need a large aquarium to live in. The tank size has to be at least ten gallons. In some cases, a larger tank would be a better option. This shall provide a good amount of space for them to move freely.

You will need a good filtration unit. The Japanese rice fish can’t survive in dirty or polluted water. Therefore, you should change the water in the aquarium regularly, as it is much healthier for them.

The aquarium needs a firm lid, because these fish have great mobility and can easily jump out of the aquarium. Surely, you wouldn’t want to have fish jumping out of the tank and roaming on the floor.

It would be recommended to have a spongy lid on top of the aquarium to enrich the water with air. Drilling a ¼” tubing or air inlet is a good option if the lid doesn’t provide the needed air support.

In addition, a well-lit environment is optimal for them. Since the Japanese rice fish naturally live in rice paddies, where there is shallow water, they receive a considerable amount of sunlight. 

The substrate of the aquarium can be covered with gravel or sand. Some plants and small driftwood would be nice for them to hide. These accessories would make them feel like they’re living in their natural home.

Rice Fish Water Parameters

Rice Fish Water Parameters

Rice Fish Water Parameters

Due to the vast difference between all fish, each group settles in a certain place under the water surface. The durability and homeostasis of the fish are two major key factors to determine the needed water specifications.

Some fish live in shallow water only. And other types find pleasure and comfort in living way deep beneath the sea, where the pressure is too high.

Brackish water is the optimum type of water for the Japanese rice fish. In nature, these fish tend to escape from the rice paddies and into the ocean for a little bit. However, they can live perfectly in freshwater, since they can be found in rivers.

They prefer to live in cold environment. The suitable water temperature for the Japanese rice fish ranges from 64 to 75 Fahrenheit. The pH of the water should be 7.0 to 8.0.

Make sure that the water is almost steady inside the aquarium, as they prefer to live-in slow-moving water.

Rice Fish Tank Mates

Rice Fish Tank Mates

Rice Fish Tank Mates

When you think of housing fish, the most important thing to keep in mind is “will these fish be able to survive with each other?”. It is necessary that you choose the right species that can coexist in harmony.

There are two types of fish; omnivores and carnivores. The omnivores are the peaceful kind that shows no violence or aggression. The majority of pet fish are omnivores.

However, some fish are ruthless predators that hunt other fish and feed on them. Putting these two types of fish in one aquarium can only have disastrous endings.

The Japanese rice fish are naturally friendly and peaceful creatures. They rarely can be aggressive. They can live in harmony with many other species.

However, make sure to put fish of the same size as the Japanese rice fish.

The reason is that these fish are very small and powerless. Therefore, larger fish (even if they’re peaceful) might see them as food.

Any fish that may show aggression or any larger fish are a clear threat to the Japanese rice fish. They can hang out peacefully around some sea creatures, like shrimps and snails.

Feeding Rice Fish

Feeding Rice Fish

Feeding Rice Fish

Since the Japanese rice fish are peaceful, they do not feed on each other or on any other fish. They are omnivores. Flakes and freeze-dried foods are the usual nutrients that you can buy them.

Sometimes, you can feed them worms or small vegetables, it wouldn’t harm them. On the contrary, some live foods have many nutrients that the fish need. You should feed them on a regular basis, at least two times per day.

Although they might need nutrients from live food, the diet must not solely stand on it. Don’t forget that first and foremost, these fish are plant eaters. Adding too much live food to their diet may change their peaceful nature.

You would be turning them into vicious carnivores slowly and gradually. Ask the person who works in your local pet store about information regarding the ideal habit for these fish.

Rice Fish Diseases

Usually, the Japanese rice fish do not easily suffer from diseases. However, than doesn’t mean that they are 100% immune to diseases. It all depends on how well you take care of your tank.

You should be careful with the water type and all the accessories you add to the aquarium. Make sure that the plants and gravel are perfectly cleaned. The dirt and bacteria might be a serious threat to the fish.

The best thing about the Japanese rice fish is that the infection isn’t immediate. You can easily notice if one or two fish show weird behavior. Thus, you can prevent the spreading of infection.

In order to prevent any upcoming diseases, make sure that the water remains clean by changing the water regularly and maintaining an efficient filtration unit. Also, maintain a healthy diet that’s full of all the nutrients that they need.

Dealing with these fish is easy and housing them shouldn’t be a problem. That’s why they are the perfect type for housing, if you’re a newbie. All you have to do is gather the information you need and you’re good to go.

Breeding Rice Fish

Breeding Rice Fish

Breeding Rice Fish

To ensure their breeding, the aquarium must meet specific conditions. You must provide the right water temperature and the right amount and kind of plants.

The plants work on attracting the fertilized eggs from the female’s abdomen and nursing the baby fish until they hatch. The baby fish should come to life after ten to twelve days.

It is usually difficult to know the gender of the Japanese rice. However, if you focus on the anal fins, you might be able to differentiate between them, as the males have larger anal fins.

Some people wonder about the exact nature of the Japanese rice fish. After all, housing and raising fish is a responsibility, as you hold their life in your hands.

So, those who are new to the field are anxious and ask many questions to be certain of what they should exactly do. Now, we shall discuss some of these questions.

Are Japanese Rice Fish Aggressive?

The Japanese rice fish are primarily peaceful creatures which do not show any signs of aggression or bloodlust. As a matter of fact, when they get nervous or anxious, they tend to seclude themselves between the plants and remain stable.

The Japanese rice fish are joyful and full of spirit. You can notice them moving all around the aquarium, whether alone or together. So, it’s very hard and very rare that they show any aggression or violence to one another.

Do Japanese Rice Fish Need a Filter?

The Japanese rice fish require specific environmental conditions in order to survive. One of them is the presence of either brackish water or freshwater. Due to the fact that the faucet water isn’t perfectly safe, it is essential to install a good filtration unit.

First of all, you have to take a sample from your faucet water, and then make a TDS (total dissolved solids) test on it. According to the result, you should know the type of filtration system that you’ll need.

Some people purchase a reverse osmosis and deionization system (RO/DI system), just to make sure that the water is perfectly safe from harmful bacteria and undesired materials.

Do Japanese Rice Fish Need a Heater?

The optimum water temperature for the Japanese rice fish ranges from 64 to 75 Fahrenheit. They prefer living in a cold environment. They can withstand living in water of moderate temperature.

However, if the water temperature is too high, their internal organs wouldn’t be able to handle it, and they’ll eventually die. So, installing a heater in the aquarium will make their death faster.

What is the Lifespan of Japanese Rice Fish?

The average lifespan of the Japanese rice fish is around four years. During this period, the fish continue to grow until they reach 4 centimeters of length.

To ensure that your fish live this long, secure a perfect, clean and healthy replica of their habitat, maintain a good water temperature and pH and continue to provide them with the nutrients they need.

Seeing these little creatures go back and forth in the aquarium will put a smile on your face. They are easy to take care of, but keep in mind that this is a responsibility.

You must be up to the task. In the end, we hope that this article gave you the right amount of information you’ll need on Japanese rice fish.

Updated: January 7, 2020 | Freshwater, Japanese Rice Fish

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