No. 7 Breeding of Orygias mekonensis | Fish production is water production

Orysias mekonensis eggs. Inside the egg is a young fish that is about to hatch.

A female swimming with eggs on her stomach after spawning (top) and a beautiful male (bottom)

first

This time, I would like to introduce the breeding of Orysias mekonensis (hereinafter referred to as Mekonensis), which I introduced last time. Mekonensis is an extremely small species of the same genus as Japanese killifish. If you keep both males and females together, spawning will not be difficult, but since the fry are so small, raising them may be a bit difficult. Therefore, here we will explain the points you should keep in mind when breeding Mekonensis.

Profile

I introduced the profile of Mekonensis last time, so I will briefly explain it here. Mekonensis belongs to the same genus Orygias as the Japanese killifish (Oryzias) and is distributed in the northeastern region of Thailand. It is extremely small with a total length of about 2 cm, and its distinctive feature is that the upper and lower ends of its tail fin are colored vermilion red. Males in particular have this vermilion red color that stands out and look very beautiful.

Mekonensis is also characterized by its different colors depending on the region where it lives. When male Mekonensis is excited, the inside of the vermilion-red color of the tail fin often turns black, but the male from Sangu, Bueng Kan Province, Northeastern Thailand, which we will discuss last time as well, has a large black area and a deep coloration. It is characterized by The contrast between the vermilion red and black is clear and the colors are truly stunning.

This beautiful color is often seen when males fight with each other, or when they appeal to females during breeding. If you keep multiple males and females, you will see them more often.

A male Mekonensis (front) appealing to a female (back). Just like during a fight between males, at this moment the male's body color becomes darker and becomes very beautiful.

Confirmation of sex

Of course, for breeding, it is essential that both males and females are present. Therefore, it is important to understand the characteristics of males and females.

●Characteristics of males
Mature males have a deep and distinct vermillion red color on the upper and lower ends of their caudal fins, and when excited, the inside of the vermillion red color turns black. Also, compared to femalesIt is also characterized by its dorsal and antler fins becoming larger and the fins becoming comb-shaped.is. When excited, the dorsal and anal fins turn black, and depending on the angle, they may appear grayish.

Mature male Mekonensis. When excited, the black color of the tail fin becomes darker and the contrast becomes clearer, making it more beautiful.

Each fin of the male is larger than that of the female, and the dorsal fin and antler fin have comb-shaped rays, making them easy to distinguish.

●Characteristics of female
Females have smaller fins than males, and their caudal fins are not as brightly colored as males. AlsoThe dorsal fin and anal fin do not have comb-like rays.So the difference is clear. Also, as spawning approaches, their bellies become larger, making the difference between them and the males even more obvious.

Mature female Mekonensis. The rows of the dorsal fin and antler fin do not form a comb shape.

The abdomen of a female that is close to spawning grows to the point of bursting. At this age, there is a high probability that they will spawn in the near future. The protruding excretory hole at the back of the abdomen is also a sign that spawning is near.

Breeding method with breeding in mind

Regarding breeding, there is no problem if you refer to the previous article, but I will list some points with breeding in mind.

●Aquarium
Spawning is possible even in an aquarium with a width of 20 cm. Introduced last timeGlass garden N230You can enjoy breeding in a small aquarium such as (230mm wide x 150mm deep x 250mm high).

Glass garden N230An example of breeding using. Please refer to the previous page for the equipment used. Even in a small aquarium, if there are mature males and females, you will likely see spawning.

●Number of animals kept
If you want to breed, you should naturally keep males and females together.To ensure spawning, it is safe to have at least two males and two females.is not it. In the case of young fish, sex differences may not be clear, so it is a good idea to keep a large number of fish, preferably 10 or more.

●Maintaining water quality
Slightly acidic water is suitable. Maintains pH around 5-6.5Fresh water is suitable for spawning, and it is not good for the water to become old and the pH to drop too much.Change the water regularly to keep it clean so it doesn't get stale. I also feel that it is not good for the moss to stand out. At the same time as water changemaintenance goodsUse it to remove moss and clean.

●Water temperature
We are currently verifying the water temperature suitable for breeding, but in my breeding environment, spawning is often seen at around 25°C, but spawning tends to stop when the temperature continues to exceed 28°C. I would like to continue observing this in the future.

●Creating an environment for spawning
mekonensis isAquatic plants are placed inside the aquarium to help you spend a calm time.To do. We recommend robust species such as Microsolum, Anubias, Watersprite, and Matsuo. Mekonensis are timid and often run away if their owners look into them, so make sure to include plenty of these aquatic plants so they can hide.

However, some eggs fall and are often found attached to aquatic plants near the substrate. ThereforePlacing willow moss etc. densely near the substrate will make it easier for eggs to attach and collect them.

In addition to aquatic plants such as willow moss, artificial egg-laying algaeThe fluffy spawning of medaka fishIt is also recommended to use .

About breeding

●Time for spawning
If you keep a mature male and female in good condition, you should eventually see the female swimming with eggs. by sexSpawning and ejaculation generally occur at dawn.Therefore, it is quite difficult to observe this situation. Parent fish often do not spawn if the breeder watches them closely.

Usually when you wake up in the morning and look into the aquarium, you'll see a female swimming with eggs attached to the back of her abdomen, near the cloaca, and you'll think, "Oh, she laid eggs." Since the male has already ejaculated, if she is able to successfully fertilize the eggs, the eggs will begin to develop.

A female with eggs on her stomach. They can be seen swimming like this for a while after spawning.

●Number of eggs laid
Depends on the size of the femaleA large female will lay about 2 to 4 eggs at a time.I think that continuous feeding of artificial feed for medaka breeding and hatched brine shrimp larvae will be effective in increasing spawning frequency and number of eggs.

Eggs attached to the female's abdomen. This female was quite large and had 4 eggs.

●Egg structure
Around the eggs, there are short hairs (fuchakumo) that grow densely, and there are long, thin, string-like hairs called fuchakushi (fuchakushi) and entanglement threads (tenrakushi), which are used to attach to objects such as aquatic plants. It gets tangled.

The adhesive thread is very strong, so if it can be firmly entangled with aquatic plants, it will not come off easily.

Structure of the egg. The eggs are surrounded by dense hairs that cling tightly to objects with strong adhesive threads.

●Attach eggs
After spawning, the female swims with the eggs attached for a while, probably because she is looking for a suitable place to attach them.

Multiple eggs are attached to separate locations, presumably to avoid the risk of being eaten. If they put all their eggs in one place, they will be quickly eaten by predators, so they probably put their eggs in various places.

The place where eggs are attached in the aquarium is mainly aquatic plants. In environments where there are many fish living together, eggs are often tangled in aquatic plants near the bottom where it is difficult for other fish to find them, and if the attachment threads are not properly tangled, eggs often fall and roll to the bottom. You can

By the evening of the spawning day, all eggs are attached to aquatic plants, etc.It rarely lasts until the next day.

●Management method after spawning
If you leave the eggs alone after spawning, there is a high risk that they will be eaten by other individuals.In environments where the aquarium is full of aquatic plants, young fish may hatch and grow from uneaten eggs, but the chances of survival are low.

thereIf you want to ensure that you get fry, keep the parent fish and eggs separate.If you can get a lot of eggs at once, we recommend moving the broodstock, and if you have a small number of eggs, we recommend collecting them and storing them in another container. If you want to keep the parent fish in the same tank,float box SIt is also a good idea to use isolation containers such as

This time, we used a small container to observe the growth process of young fish.Showbetta Collection Case MI tried using (width 130 x depth 80 x height 150 mm). If there are only a few fry, aeration is not necessary if you add aquatic plants. In my case, I keep the case in a room where the temperature is controlled by an air conditioner all year round, so controlling the water temperature is easy, but if you need to keep it warm,aqua panel heaterIt is also recommended to use a heat insulator for small cases such as .

Showbetta Collection Case MRaising fry in a small case (130mm wide x 80mm deep x 150mm high)

Incidentally,A cloudy white egg is a dead egg.is. Eggs can die for a variety of reasons, including unfertilized eggs, failure to develop, or mold growth. If you find such dead eggs, remove them immediately.If you keep multiple eggs together, remove them immediately as mold that develops on dead eggs may have a negative effect on other healthy eggs.I want to keep that in mind.

A dead egg. I want to remove it from the aquarium as soon as possible because there is mold.

●Number of days until hatching
The fertilized eggs continue to develop day by day, and soon you will be able to see the appearance of a fry inside the eggs.The general number of days until hatching is around 25 days at a water temperature of about 10℃..

The eggs I observed this time were kept at 24 to 26 degrees Celsius for about 11 days. The cumulative time until hatching is 24 hours x 11 days = 264 hours.

In the case of Japanese medaka, it is generally said that they are incubated at 25℃ for about 10 days or 250 hours, and in the case of Mekonensis, a certain amount of time, similar to Japanese medaka, is required before hatching. .

●How to raise fry
The fry are expected to hatch between night and early morning. Immediately after hatching, the young fish are very small, about 1.5 mm in total length, and spend the first day after hatching absorbing nutrients (egg yolk) from their stomachs without eating.

From the second day onwards, they search for food just below the water surface, occasionally taking tiny objects into their mouths. They probably feed on microscopic organisms and organic matter that occur on the water surface, but it is difficult to prepare such things. ThereforeAfter the fry hatch, if you grind up aquatic plants and float them on the water surface, or sprinkle a very small amount of baby food for medaka on the water surface, the naturally occurring microorganisms will become food.It seems that. At this point, the baby food for medaka is too large for the young mekonensis to eat.

As the fry grows day by day, they gradually respond to baby food and appear to take it in their mouths. If it grows smoothlyThey will be able to eat paramecium about a week after hatching.Therefore, prepare it in advance and give it in small amounts with a pipette. If they eat it safely, they will grow faster, so I would definitely like to feed it to them.

Paramecium is a very small microorganism that is also used for cultivating medaka fish, and it can be cultured by obtaining the seed parent and feeding it. Seedlings and food can be purchased at shops that sell a lot of killifish or by mail order, so it is a good idea to cultivate and maintain them yourself. You can easily cultivate it if you get the hang of it.

For a while, feed baby food and paramecium together to encourage growth.In my case, I basically fed them three times a day, in the morning, afternoon and evening, and occasionally when I felt like it.

It depends on the growth condition of the fry, but approximatelyYou will be able to eat the hatched brine shrimp larvae about 25 days after hatching.If you eat several brine shrimp larvae in one feeding, your stomach will swell quickly, which shows how small the fry are. If you can eat brine shrimp larvae, they will grow even faster, so prepare this in advance.

Brine shrimp larvae are highly nutritious food that can also be fed to parent fish, so it's a good idea to have them on hand. Brine shrimp can be purchased as dormant eggs at shops or online, and the larvae are hatched in 1-2% salt water (suitable temperature is 25-28℃) and then fed. Once you get used to this, you can easily hatch them.

Once the brine shrimp grows enough to eat brine shrimp, they will become more active and should be able to be kept and managed in the same way as their parents. This time I will continue to follow the growth process.Showbetta Collection Case MI managed it with

A fry 81 days after hatching. Eating artificial feed for medaka floating on the water surface

Tips for changing water and maintaining the breeding environment
This time, I changed the water for the first time more than 45 days after hatching, but until then I had been adding water from time to time to cover the evaporated water. The water for replenishment was descaled tap water and adjusted to a pH of about 6. I changed the water to about 1/2 of the total amount of water, but there was no problem. We use tap water that has been adjusted in the same way as added water.

As you continue to manage the fry, moss will become noticeable on leftover food, aquatic plants, and glass surfaces. Therefore, I added two snails to help dispose of leftover bait and remove moss, and they have been very useful.In addition to snails, small shellfish such as red ramshorn are also useful.So it's a good idea to use it. However, it is not possible to completely remove moss from the glass surface with monoaragai, so when changing the watermaintenance goodsIt would be a good idea to use it to clean it.

Monoaragai are useful for processing leftover bait and removing moss. They tend to be disliked in aquariums because they grow in large numbers, but depending on how you use them, they can become a reliable ally.

If you put in the oysters, their droppings will become noticeable, so it's a good idea to suck them out with a tube when changing the water.

Egg development and fry growth records

Now, I would like to report on the development of eggs and the growth process of young fish of Mekonensis from Sangu, Bueng Kan Province, which I introduced this time. I would be happy if it could be used as a reference when actually breeding.

●Aquarium
In addition to the aquarium introduced earlier, spawning was also observed in a 20cm x 20cm cube aquarium. In the cube aquarium, they cohabitated with Boraras, an ultra-small species of the carp family, but the eggs developed without being consumed, so we decided to keep an eye on them in the same tank, and just before they hatched, we placed them in a container for raising the fry.Showbetta Collection Case MI decided to move to.

●Water temperature
Spawning was observed frequently at temperatures between 24 and 26 degrees Celsius.

●Record of eggs and fry
Day 1: Egg confirmation

Fertilized eggs on the first day after spawning. Very small, about 1mm in diameter. Live eggs are highly transparent, and attached hairs and attached threads can be easily seen. The grains visible inside the eggs are oil droplets that provide nutrients for the fry. Cell division begins from the opposite pole of the oil drop and development progresses.

Fertilized eggs on the first day after spawning. Tangled in aquatic plants with adhesive threads

Day 2: Outbreak progresses

Day 3: Outbreak progresses

Day 4: Check the head and tail

Development progressed further and a head and tail were formed.

Eggs on the 4th day. Changes can be seen, such as being swayed by the water, positioning itself on the surface of the leaf, or hanging by attached threads. Occasionally, the parent fish approach, but there are no signs of them trying to eat. Boraras, who lives with me, sometimes pokes me, but I can't seem to eat it.

Day 5: Outbreak progresses

Day 6: Check your eyes. Each part of the body is formed

My eyes are starting to understand. The tail becomes clearer too.

Day 7: Outbreak progresses

It's so small compared to the parent fish, which has a total length of about 2cm! They are tangled in aquatic plants with attached threads, but sometimes become suspended in the air.

Hanging from aquatic plants. Eyes can be seen inside the egg

Day 8: Eyes and tail can be clearly seen

The eyes are more noticeable and the head and tail can now be clearly seen.

Day 9: Eyes become clearer

The eggs seem to be very strong and can sometimes withstand being violently handled by the parent fish.

10th day: Eyes become larger and more prominent, and the head becomes clearer. Move to another case

My eyes became clearer and I started to understand my body. As hatching is getting closer, please add it to the breeding water.Showbetta Collection Case Mmove to

11th day: It looks like a fry and hatching is finally near.

First photo taken after moving to the case. Same cut as the first photo. I could understand the body better and it looked more like a fish. close to hatching

You can clearly see the eyes inside the egg. It's finally getting closer to hatching

Day 12: Hatching early in the morning

Egg shell after hatching. The eggs that protected the fry for about 11 days have finished their role.

1st day after hatching: Birth of a small baby

When I looked into the tank at 9am, it had already hatched. It is small, about 2 to 3 mm in total length. It must have hatched early in the morning because it had not hatched late at night the previous day. They can already swim freely, but they often stay on the sides or near the middle of the tank. It seems that it is absorbing the egg yolk from its stomach and has not shown any feeding behavior yet.

2nd day after hatching: Shows feeding behavior on the water surface

In the morning, we observed young fish searching for food near the water surface. An oil film (biofilm) forms on the water surface. I am feeding the medaka baby food ``Kyorin Medaka Baby Hyper Nurturing/20g'' (hereinafter referred to as "baby food"), but the fry's mouths are too small to eat. It seems that they are eating some kind of microorganism. The stomach is slightly swollen, but it is unclear whether it is egg yolk or food.

3rd day after hatching: Move around in the tank. Add a small amount of baby food in the morning. She is responding, but it is unknown if she is eating. When I took a photo and enlarged the abdomen, the abdomen was yellow. I can't tell if it's food or egg yolk, but the young fish seem to be poking at food on the surface of the water, so they may be feeding.

A young fish exhibiting feeding behavior near the water surface. They may be eating bits of baby food or naturally occurring microscopic organisms.

4th day after hatching: Searching for food just below the water surface. Judging from the way their bellies swell, it appears that they are eating tiny creatures. I am feeding her a very small amount of medaka baby food, but it is unknown if she is eating it.

9th day after hatching: When I gave them paramecium for the first time, they ate it.

10th day after hatching: They have grown considerably

Total length approximately 6mm. A red color can be seen at the base of the tail fin. The white oval-shaped thing visible above and above the snout of the young fish is a paramecium. If they can eat paramecium, they will grow faster. From then on, feed paramecium and baby food at least 1 times a day until you can eat brine shrimp.

12th day after hatching: First confirmation of eating baby food. You may have eaten it before without even looking.

24th day after hatching: Confirmed feeding of brine shrimp larvae for the first time. I have given him brine shrimp larvae several times, and although he shows interest, he doesn't eat them, probably because they don't fit in his mouth. It's adorable how your stomach gets full after feeding a few fish.

30th day after hatching: Since they started eating brine shrimp larvae, their growth has become faster.

34th day after hatching: It has grown and started to look like a parent fish.

Total length about 1cm. It actively eats brine shrimp larvae. A vermilion red color can be seen at the end of the tail fin, and a metallic shine can be seen at the end of the abdomen and anal fin.

Fry eating brine shrimp larvae

39th day after hatching: Add two small oysters to dispose of moss and leftover food in the tank.

40th day after hatching: First water change. Approximately 1/2 of the total water volume. The water used for water changes was descaled from tap water and adjusted to pH 6.

78 days after hatching: They have grown considerably larger. Understand gender differences

They eat brine shrimp larvae and baby food every day and grow to a total length of about 1.3 cm. Black pigment can now be seen inside the vermilion-red color of the tail fin. The anal and dorsal fins are comb-shaped, so it is likely a male.

A fry 78 days after hatching. He's already starting to look just like his parents.

in conclusion

This time, following the previous article, I would like to introduce the breeding of Mekonensis, but what did you think? There is a lot of work involved in everything from spawning to raising the fry, but it's a lot of work, but it's fun, and I'm very happy when the fish grow safely.

When you actually take care of eggs and fry, I think you'll see a lot of things that need improvement. For example, you will be acutely aware of the importance of initial feed in order for fry to grow smoothly. So I started thinking about whether it would be possible to grow them faster in the summer if they were grown outdoors like Japanese killifish. I would like to find an opportunity to verify this. Everyone, please try breeding small Orygias such as Mekonensis. It is fun.

see you!

No. 7 Breeding of Orysias mekonensis