Usually an iridescent milky white color, these beautiful fish are a lovely addition to any fish tank. Betta fanciers will be happy to know this variety of betta fish is not hard to find.
The subject of betta genetics is interesting and complex. Opaque Bettas differ from Pastel Bettas and other betta varieties by having the Opaque (Op) gene.
The opaque coloration in bettas is usually achieved through selective breeding for the opaque factor.
Table of Contents
What is an Opaque Betta?
The term “opaque” refers not only to the white betta fish.
There are three forms of opaque betta fish: blue (as in royal blue), steel blue, and green. Most often, when people say “opaque white bettas,” they are referring to steel blue genetically.
Steel blue bettas often have a “blue wash” to their appearance. Blue and green opaque bettas have a blue or green coloration.
The term “opaque” means the fish has the opaque gene. It is not necessarily white, but most commonly, the fish appears opaque or misty white with hazy eyes.
Sometimes solid colors are referred to as opaque, but usually, when people refer to an opaque betta, they mean the milky white color.
You need to look at the fish’s sheen to determine what opaque it is.
The International Betta Congress (IBC) standard defines opaques as:
“Non-red, light-bodied fish similar in appearance to pastels. However, there are guanine deposits, giving a denser, milkier, appearance, and opacity to the coloration of these fish. These deposits are most visible around the head and eye and continue to accumulate as the betta ages.”
An opaque betta is also not an albino betta fish, which is rarer. The albino betta has no color pigmentation and has pink or reddish eyes.
Opaque bettas are also not translucent.
Are Opaque Bettas Rare?
A pure opaque white betta is not common but is achieved by a good breeder.
Opaque bettas come with different kinds of fins and tails; a half-moon tail is common. Most pet stores carry veil tail bettas.
A veil tail has a long tail swooping up and then curving back down. The anal and dorsal fin are also long and droop down from the caudal peduncle.
Opaque bettas are available on the market but are more expensive than a more common betta. The price increases with the complexity or rarity of the fish’s body and tail type.
A White Opaque Betta costs about $16.00.
A White Opaque Halfmoon Singletail Male costs about $30.00.
A White Opaque Male Plakat Betta fish costs about $40.00.
Opaque white bettas were developed around 1960 by Dr. Gene Lucas, a betta specialist.
One or more parent bettas must have the opaque factor to produce an opaque betta. The opaque factor becomes more visible if both parents have the Op gene.
The genetic makeup of the opaque white betta is: C Bl Si Nr Op
- C is the Cambodian gene for lack of dark body pigment
- Bl is the steel blue pigmentation looking silver-white when on a light background
- SiGives a spread of iridocyte pigment – which gives it metallic reflective qualities
- Nr is Non-red, meaning the fish cannot produce a red pigment
- Op is the Opaque gene causing opacity
In this case, Si is dominant. C and Nr are recessive, and Op is semi-dominant. One expressed allele for opacity is detectable, but two alleles are very obvious.
Op is the gene characteristic of opaque betta fish. It gives a white, powdery appearance to the fish.
Opaque is not a common betta fish color.
Problems with Opaque Bettas
Since the fish is white, it shows up any defects quite well. Defects such as black lips or scales will be very visible.
The white coloration does not blend too well with the underlying yellow color of a betta.
This frequently makes the fish look yellowed. There are strains with a slightly blue tinge, too, particularly on their fins.
Opaques often have poor-quality fins. They have been bred so much for their opaque gene; their fins are neglected.
The gene responsible for opacity also causes more internal organ problems than other common betta fish varieties experience.
On a positive note, opaques are slightly less aggressive than some other strains of betta fish. This is a pleasant characteristic for newer fish keepers.
Opaque versus Pastel Betta
The opaque and pastel betta are two very popular betta variants. They differ in only one gene.
The genetic makeup of a pastel betta fish is almost identical to the opaque. The opaque gene, however, is not always expressed in a pastel.
Thus, opaque bettas are also pastels but have more of the opaque gene. Pastels are not also opaques.
If a fish has too little opacity, they come out with a translucent appearance. If they have too much, they come out opaque.
A high-quality pastel betta has to have some opaque factor. Crossbreeding pastels will increase the number of opaque factors down the line.
The trick to telling an opaque apart from a pastel is the “white” pigmentation looking thick and powdery on the fish. This is best done from a view from above the fish.
The dense pigment on an opaque covers the fish’s entire body. This includes the nose.
In a pastel betta, the pigment usually does not go as far up, or if it does there is not much. Looking at the fish from above will help you discern whether or not you are looking at a pastel or opaque betta.
Pastel bettas have iridescent steel blue, blue and green coloration. Regular dark-bodied iridescent bettas do not have the Nr (or Cambodian) gene.
Pastel bettas are homozygous for the Nr gene. This gives them their trademark light flesh-colored bodies.
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