Betta genetics can be very complicated or very simple depending on what we look at. Before I attempt to explain any genetics however there are a few general (very oversimplified) laws of heredity you should know (for those somewhat familiar with genetics, skip ahead of all this mumbo jumbo).
To begin with, for each characteristics every organism inherits two genes, one from their dam and one from their sire. Bettas are made up of millions of these gene pairs. An organism's genetic make-up is called it's genotype. Basically, these gene pairs are what determine an organisms physical appearance. The physical appearance of an organism is referred to as it's phenotype.
Each characteristic generally has a recessive and dominate form of a gene. When there are two different forms of a gene the forms are called alleles (i.e.: the dominant allele and the recessive allele). If an allele, in a pair of genes, is dominant, the dominant copy overrides a recessive copy. The only way a recessive gene is expressed is if there are two copies of it. An organism with two same copies of a gene (either dominant,dominant or recessive, recessive) is referred to as homozygous. When two homozygous organisms are crossed their offspring are all homozygous for that trait. An organism with two different copies of a gene (dominant, recessive) is call heterozygous. When two heterozygous organisms are crossed half of their offspring is heterozygous and half is homozygous. Confused yet? Don't worry - you will catch on!
Lets begin with a simple dominant/recessive gene - the gene that make a Betta either a single tail or a double tail. In Bettas, a single tail is dominant to a double tail.
Photos provided by Liz-Hanh Morin
When we cross two Bettas their offspring's phenotype depends on the alleles present in the parents' genotype. If we cross two double tail Bettas we know that they are both homozygous and therefore all of their offspring will be double tails too. We can use a table to demonstrate how this works. Middle, right hand squares represent 25% of a spawn.
Now what happens if we cross two homozygous, single tail Bettas? All of their offspring will be homozygous single tails.
Allrighty, now that you're an expert, let's try something a little bit trickier. Let's cross a double tail to a homozygous single tail. Come on, quit sweating! Just examine the table below. Remember, the single tail is dominant to the double tail and one single tail S will override a double tail DT.
See now that wasn't too bad was it? Ok, now for the real quiz! What will you get if you cross a heterozygous single tail to another heterozygous single tail?
Ok, last question. What happens if you cross a heterozygous single tail to a double tail? What about a heterozygous single tail to a homozygous single tail? Fill out the form below and I'll tell you if you are right.