Observations On a New Giant Betta Splendens

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By Linh Nguyen Updated on 26 Feb 2023

The following article was written by Dr. Gene A. Lucas. Original article published in FAMA magazine. Here is the article content.

Just about when I thought I had seen them all, still another type of domestic Betta splendens showed up at the Orlando IBC Convention in 2002. They were being called Giant Bettas. They were intriguing to me because in the scheme of things one of the drawbacks to Bettas as aquarium fish has been that they aren't very big. It has been a general consensus that, all other things being equal, larger size would count as a positive when judging Bettas and I believe it is so stated in the IBC judging standards.

A New Giant Betta Splendens

A New Giant Betta Splendens

There is no question that larger fish dominate the hobby worldwide and that it has long been that way. The hobby really commenced with the keeping of colored carp (Goldfish and Koi), both being species which can develop to large size, and both still are most popular in some areas. Other popular species, especially in the Orient, are Dragon fish (Asian Arowana), Discus, and various other Cichlids including one being called "Flower Horn" which seems possibly to be a hybrid of some types of new world species. Both Discus and the Flower Horn are being produced in steadily increasing numbers of color variety.

Getting larger Bettas in domestic stocks is nothing new. Most strains over time have continued to get larger. I would attribute this to either inadvertent or purposeful selection for larger size and of course better care and improved diets. We can easily see the progression in size that has happened in humans. Look at our young people, basketball and football players in particular. I don't think my college team had anyone over six foot three and if they had a six nine or ten player he was big. A seven footer in the fifties was a novelty. Today almost every basketball team has someone six ten or seven foot. I am just under six feet tall and I can walk the streets or the mall and regularly encounter young women who are taller than I am. I am sure you have all noticed the same. Conversely, most of us can look at parents and grandparents, most of whom were smaller than we are.

Size in football players is just as obvious. Mention of a six foot seven inch, 325 pound man who could run in the fifties would have been like a dream to a football coach, but today most coaches have a half dozen or more players in that category. Professional teams, most college teams and even some high school teams can probably field entire offensive lines made up of 300 pounders.

But this isn't about big humans.

The point here is that something or some combination of things in our lives today supports superior growth and it doesn't seem strange that the same thing might happen with other domestic creatures, including our fish. In Bettas there are clear relationships to such things as environmental quality and superior diet. Those who produce the bigger fish will be found changing water more frequently and often treating it in many ways such as RO (reverse osmosis), adding buffers to sustain more constant pH, adding salt or products to control ammonia compounds, or whatever. They also go to greater efforts to feed varieties of food, especially live foods, which may include raising white worms or adult brine shrimp or regular treks to the fish stores for live brine shrimp, glass worms, or black worms. These efforts keep the fish in more vigorous health and provide them with what they require to do their best growing.

1. What Are The Giant Bettas Like?

I assume not many readers will have had a chance to see these Bettas yet. I haven't seen or heard of any appearing in fish stores but they have been offered (sparingly) on AquaBid. None have been offered for sale by IBC members to my knowledge. The ones in the IBC Convention were offered for auction with $100.00 minimum bids. I don't recall anyone bidding on them but I and one other person each purchased one for the minimum.

These Bettas were entered in the color and form variations class as I recall; although they were of several color types, they represented only a number of those already existing. There were dark bodied and cambodian types, blues, greens, some with non-red (yellow), blacks, reds, etc. There were some with the Butterfly pattern (fins one color halfway out and another color the rest of the way). I remember specifically one each of a blue and a black Butterfly, the entire collection of fifteen or twenty individuals was kind of a sample of a bunch of the regular colors seen in modern domestic Betta stocks.

The most obvious feature of the Giant Bettas was their size. Mine was nick-named "Bubba" which just seemed to fit. Photographs are not helpful to try to visualize size unless they are placed with some measuring device for comparison and I haven't seen any presented this way. I am providing a sketch here to show the approximate difference between typical examples of wild types, domestic types of regular size, and the Giant Betta I have which seems typical of those in the IBC show (Figure 1).

Since the caudal (tail) fins vary in length (proportionate to the body), I measured the body length from the tip of the snout to the base of the caudal fin (called the "standard length" by ichthyologists) on three average-sized Bettas from three different groups for comparison. I used as wild type one typical of those we recovered from Malaysia and Vietnam (I'm suspicious of those collected in many parts of Thailand since they often show domestic color variations and are possible escapees, discards or hybrids from domestic stocks). I used an average-sized fish from my own fishroom to represent the domestic types and I used Bubba as an example of the Giant Betta as he is typical of those I saw. The measurements were as follows:

  • Wild type: 3.2 cm (approximately 1-1/4 inches)
  • Domestic: 3.7 cm (approximately 1-1/2 inches)
  • Giant: 6.6 cm (approximately 2-5/8 inches)

While the difference in the length between wild type and "ordinary" domestic Bettas is marginal, the difference between them and the Giant is significant. The domestic Betta is 1.156 times as long, and the Giant 2.06 as long as the wild type; over twice as long.

Another parameter that can be used to compare size is weight. I weighed them with a laboratory triple beam balance and came up with the following:

  • Wild type: 1.2 grams
  • Domestic: 1.95 grams
  • Giant: 8.85 grams

The difference in weights is a little more telling. The domestic Betta was 1.625 times that of the wild and the Giant was a healthy 7.375 times as much. Of course there would be differences in each fish's total tissue density due to the presence (and kind) or absence of food in the intestinal tract, amount of "space" in the gas bladder, the relative amounts of fat to muscle and so on. Also, when the total fish is weighed, the fins are included and the amount of finnage per fish is not necessarily proportional.

I also tried measuring the volume of each fish by placing them in graduated cylinders and trying to get water displacement values but the small volumes generated from the cylinders required to hold the fish were not discernible. I am aware that each of these methods introduces an increment of error but anyway you look at it, it is clear enough that the Giant Bettas are significantly larger than the regular ones.

Giant betta compared to a normal sized betta plakat.

Giant betta compared to a normal sized betta plakat.

2. Genetics Of The Giant Bettas?

I purchased Bubba specifically to try to mate with females I had at home in my fishroom which seemed large enough that I might hope to get spawns from them. I had several females I was keeping from a spawn that had produced unusually large fish, although they were still much smaller than he was. I obtained two spawns from this male in just two tries. Both spawns contained very large numbers of fry. Space limitations kept me from trying others. Even after losses and giving away some, I got an actual count of 732 maturing offspring from one of the spawns - by far the largest I have ever reared.

One spawn was with a cambodian doubletail female with very little iridocyte color. It had huge numbers of fry but unfortunately they came down with a massive velvet infection at about one week of age and they were all lost. They were too small to classify in any way so I missed the opportunity to learn anything about the inheritance of standard traits or any new ones, especially the Giant vs. normal-sized situation.

I had better luck with the other spawn. The second female was a blue/red multicolor from a long-finned strain. She was descended from a series of matings leading back though a very large-finned steel blue male I purchased at an auction and a doubletail steel blue female tracing to a spawn of my own which originated with a show quality black male from IBC member Dan Young and a show quality yellow doubletail female I got from a different auction. I have no background data for the auction fish but their phenotypes provided me with long fins, doubletail, extended red and non-red, steel blue, cambodian, and both spread and limited iridocyte distribution.

Bubba was (he has since passed on) a short-finned green multicolor with yellow (non-red) replacing red. The two provided me with several traits I could examine. In addition to the Giant trait vs. more or less normal domestic size, there was long vs. short (normal) fins, blue vs. green (normal) iridocyte color, spread iridocytes vs. limited (normal), and non-red (yellow) vs. red (normal). Although both parents were dark, the spawn also included light bodied (cambodian) fish, indicating that both parents carried that recessive gene.

What I obtained from this spawn was pretty much predictable. They tend (at about six months of age) to be average sized for domestic Bettas although some are slightly larger. At this point none seem anywhere near the size of their father. I have been told that the Giants tend to develop as they grow older but this is something I will have to wait for to see. The males all appear to have long fins (a dominant trait from their mother) although the tails are not as big proportionally as those in her ancestry. This trait doesn't reveal itself in females. There are no doubletails.

What I did get in the spawn is an absolutely delightful array of color types. Most of them could have been predicted from the color and determinable genotypes of the two parents but there were some that I wouldn't have. Although I haven't attempted to classify them, I can summarize what is there from "eye-ball" examination. I think the easiest way to do this is to consider each color element separately so the quantity and complexity of their variety can be better comprehended.

1. The progeny presumably had a 50% (each) of being male or female. We were unable to find heterogametic males in some karyotype studies and spawns can deviate widely from a 1:1 sex ratio so this expectation may not necessarily be valid. Final sex determination may depend on numerous external influences. Female to male sex reversal also occurs almost routinely.

2. All male progeny from this spawn show large fins but would carry short fin from their father. If the female (their mother) had carried it, then one half of all progeny should have had short fins and none of them did.

3. The iridocyte color of the male was green and the female blue which means that one half of the progeny should be blue and one half green (blue is heterozygous). That is what turned up.

4. The spread of the iridocyte color is medium in both parents. The variation of spread is pretty much continuous but can be dealt with as though it occurs in three classes: heavy density, medium, and limited. The parental condition should provide for all three types in the progeny and it did.

5. Both parents are dark but both carried the cambodian gene for light body. This was demonstrated by the appearance of light-bodied progeny in the spawn. Since it is a simple recessive trait, 25 percent would be the theoretical expectation for light-bodied fish here and that seems to be what I got.

6. The female showed red but the male was yellow (non-red). The presence of about half non-red progeny showed that she carried non-red (the presence of any at all would require it). All progeny at least have one non-red gene from their father.

7. I got a few individuals of the type I called "Grizzled" but I haven't really worked out an understandable genetic pattern for them. These fish have smaller spots scattered over them with a few slightly larger blotches. They may be a version of marble but no other marble patterned fish turned up in this spawn.

8. Although no doubletails turned up in the spawn, the female could have carried it as a recessive (through her own pedigree). If she had, she would have passed it on to one half of the progeny which, if any one of them ever gets mated with another who carries it, could then resurrect the doubletail trait.

9. Behaviors were not considered in the mix but there are definitely differences in aggressive levels in different strains of domestic Bettas so it could have been. Bubba appeared to be a larger version of the domestic short-finned Bettas used in the Orient for fighting. He was not noticeably aggressive, however, and the female was typical of domestic show type Bettas. They spawned readily and without incident.

3. Discussion

This collection of variable traits (in the two parents) contains the genetic potential for producing a bewildering array of genotypes and phenotypes in the spawn. When I referred earlier to a "delightful array" of colors it was because of this potentiality. Think of all the different possibilities. They range from both light and dark fish with almost no visible iridocyte color through assorted variations of what we would call blue and green multicolors (with either red or yellow as the secondary color) to dark or light solid greens and blues.

To pick an example, I had some very beautifully colored green pastels. To get one of those I needed to have a genotype which provided green heavily spread iridocyte color, a light body and non red. (I'm disregarding variations in fin types, body size, or other possible variations here.)

Because of the mode of inheritance of each sub element of a phenotype, these do not appear in the same numbers. We can get a little practice using probabilities to predict the possibility of getting a given type. Using the green pastel example it would be as follows: one fourth would be expected to be light bodied; one half, green colored; one fourth spread iridocytes, and one half, non-red. The product of these is one in 64. I have provided a chart which shows the assorted possibilities (see Figure 2).

Although the Giant Bettas are large, those having long fins do not seem to have the fin size proportionally larger than the body that we see in ordinary-sized Bettas. I'm not sure if there is any significance to this but it triggered questions in my mind. I wondered if they might have been the result of some kind of hormone treatment. The sample was small so I concede that the few long-finned males that were there may not be representative of the type. I have seen the same thing in regular Bettas. Nevertheless, I would like to have seen some that had the full finnage of our best normal-sized show Bettas.

Are Giant Bettas for real? I mean are they true genetic type? Is there a gene for Giant Bettas? Are they the result of long and careful selection or are they the result of some kind of chemical growth stimulation! Can we expect to see significant increases in the size of our show Bettas? If so, are they going to be acceptable to the Betta "community?" These are all questions I am not yet able to answer. I hope to be able to say more after I have the results of more breeding experiments and after I can learn more about who produced them and how.

Stay tuned.

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