How to breed Japanese Blue Grass Guppy – Part I: Genetic formulas for Blue Grass Guppy

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Blue Grass are one of most popular guppies in the world. They are famous for their large dorsal and caudal fin with unique black speckles. The speckles are dense and well-distributed. That makes the fins look like grass. So, this strain got its famous name “Grass”.  

Blue Grass Guppy

Starting today, we plan to write a new series of articles. In these articles, we will talk about how to breed Blue Grass Guppy, and how to choose the parent fishes, and how to pick the proper offspring according to Mendelian inheritance, what is the genetic formula for Blue Grass Guppy and so on.

This is the first article, let’s talk about the genetic formulas for Blue Grass Guppy.

Black speckles on caudal fin

The black speckles on caudal fin are controlled by a dominant gene on sex chromosome. That means the next generation will get unique black speckles as long as dad or mom has the speckles. We only need to pick one guppy who has black speckles on caudal fin as the parent fish, all the babies are Grass Guppies. However, the difficult point, but also the key point, is that we need to maintain or improve the expression of the black speckles. Still need to be very careful when choosing parent fishes. We will talk this topic in the future.

The “BLUE” color

Different from black speckles, the BLUE color is controlled by a pair of genes on autosome. The dominant gene is B, and the recessive gene is b. There are three combinations: BB, Bb, bb. The Bb combination gives us Blue Grass, and if the genes are BB, we will get Red Grass, and we called bb as Asian Blau. (What is Asian Blau? Please see this article)

BB: Red Grass

Bb: Blue Grass

bb: Asian Blau

Asian Blau

According to Mendelian inheritance, there are six different situations, see the formulas below:

_______________Parents_____________________________Child______________________

  1. Blue Grass(Bb) × Blue Grass(Bb) = 50% Blue Grass(Bb) + 25% Red Grass(BB) + 25% Asian Blau(bb)
  2. Blue Grass(Bb) × Red Grass(BB) = 50% Blue Grass(Bb) + 50% Red Grass(BB)
  3. Blue Grass(Bb) × Asian Blau(bb) = 50% Blue Grass(Bb) + 50% Asian Blau(bb)
  4. Red Grass(BB) × Asian Blau(bb) = 100% Blue Grass(Bb)
  5. Asian Blau(bb) × Asian Blau(bb) = 100% Asian Blau(bb)
  6. Red Grass(BB) × Red Grass(BB) = 100% Red Grass(BB)

Our friends, you maybe notice the formula 4. All the children of Red Grass and Asian Blau are Blue Grass. Does it mean that the breeding of Blue Grass Guppy is very easy and efficient? We’re afraid it’s not that simple. We will talk about which is most suitable or most commonly formula used to breed Blue Grass Guppy in the next article, stay tuned.

Related posts

Three kinds of most popular Guppy in Japan – Blue Grass

How to breed Japanese Blue Grass Guppy – Part I: Genetic formulas for Blue Grass Guppy

How to breed Japanese Blue Grass Guppy – Part II: Which formula will we use

How to breed Japanese Blue Grass Guppy – Part III: Key points for picking a male Blue Grass as parent fish

How to breed Japanese Blue Grass Guppy – Part IV: Key points for picking a female Grass Guppy as parent fish

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4 thoughts on “How to breed Japanese Blue Grass Guppy – Part I: Genetic formulas for Blue Grass Guppy

  1. […] article Part I, we introduced 6 formulas for Grass Guppies breeding. Here they […]

  2. […] How to breed Blue Grass Guppy – Part I: Genetic formulas for Blue Grass Guppy […]

  3. […] How to breed Blue Grass Guppy – Part I: Genetic formulas for Blue Grass Guppy […]

  4. […] How to breed Japanese Blue Grass Guppy – Part I: Genetic formulas for Blue Grass Guppy […]

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