Dwarf aquacultured fish?

[Stoney]

The variety of aquacultured clownfish never ceases to amaze me. It makes me wonder if any breeders are selecting for smaller size. Imagine having clownfish with an adult size of 1" that could comfortably live out their entire lives in a 5 gallon pico tank. Or maybe even yellow tangs that reach 2" suitable for nano tanks. Dwarfism isn't uncommon in nature and doesnt appear to be unhealthy as far as I'm aware.

Hopefully someone with in depth knowledge sees this and can comment on the safety/practicality. Am I just dreaming or would this actually be possible in the near future? All I know is I'd be willing to pay up big time.

 

[Jay Hemdal Verified Community Expert]

The variety of aquacultured clownfish never ceases to amaze me. It makes me wonder if any breeders are selecting for smaller size. Imagine having clownfish with an adult size of 1" that could comfortably live out their entire lives in a 5 gallon pico tank. Or maybe even yellow tangs that reach 2" suitable for nano tanks. Dwarfism isn't uncommon in nature and doesnt appear to be unhealthy as far as I'm aware.

Hopefully someone with in depth knowledge sees this and can comment on the safety/practicality. Am I just dreaming or would this actually be possible in the near future? All I know is I'd be willing to pay up big time.

Interesting question!

Are there any freshwater fish that are bred for a small size? I can't think of any offhand. There are obviously breeds of dog that are different sizes. Cats on the other hand are more similar in size (teacup cats would be super popular, but there aren't any). There may be a genetic factor at work that precludes captive strains of "dwarf fish".

Jay

 

[fish farmer]

I've always wondered this myself now that tangs are getting bred.

I see a range of sizes in domesticated trout. We never try to raise or select for the runts. I have noticed on one of our steelhead lines that the larger fish tend to not breed for us at year three or four so the line tends to be smaller (by selecting the 3 year ripe fish) than another faster growing line. Even the wild population of these fish never seem to reach the larger sizes with see with the other strain. The faster growing fish of the smaller strain "may" have a heart condition that leads to mortality as well.

We also have a heavily domesticated line of rainbows which has a large population of runts, which could be from inbreeding. The little ones eat like pigs, but just don't grow. We are actually investigating a new line to replace them.

 

[DeniseAndy]

Unfortunately, with dogs, they breed them large or small and end up actually causing many health issues. Too many inbred and for traits that harm them. I hate this part of any breeding.
I am betting that the smaller bred do have some health issues just as the larger ones would. Trying to capture the one trait will more than likely lead to other not so good traits or health issues.

 

[Jay Hemdal Verified Community Expert]

I've always wondered this myself now that tangs are getting bred.

I see a range of sizes in domesticated trout. We never try to raise or select for the runts. I have noticed on one of our steelhead lines that the larger fish tend to not breed for us at year three or four so the line tends to be smaller (by selecting the 3 year ripe fish) than another faster growing line. Even the wild population of these fish never seem to reach the larger sizes with see with the other strain. The faster growing fish of the smaller strain "may" have a heart condition that leads to mortality as well.

We also have a heavily domesticated line of rainbows which has a large population of runts, which could be from inbreeding. The little ones eat like pigs, but just don't grow. We are actually investigating a new line to replace them.

I've been line breeding some Victorian cichlids since 1993 and they have begun to show dwarfism, but we can't tell if it is genetic or environmental (like bluegills in a farm pond).

Many/most captive bred marine fish (except clowns) are bred from F1 stock, the offspring are not raised up for future breeding, so no worries about inbreeding depression with them.

Jay

 

[Stoney]

Cats on the other hand are more similar in size (teacup cats would be super popular, but there aren't any).

Forget about amazon and tesla, whoever figures out teacup cats will definitely be the first trillionaire hah

Appreciate the details @fish farmer

From what you guys are saying, seems like abnormal size is usually associated with health issues. But does one necessarily cause the other or is inbreeding simply causing two otherwise unrelated effects?

If it's just a lack of genetic diversity, I imagine some strategic collecting/breeding would solve the problem right? Most dogs are bred for specific personality or looks which are probably harder to come by than small size. It doesnt seem like it'd be that difficult to find under average size fish from genetically distant groups, especially for a more common/widespread species.

 

[Tamberav]

They already have a small cat breed. It is called a Singapura. Females 4-6 lb and males 5-8lbs. It is a rare breed though.

 

[Rjramos]

This is one of Miguel Hurtado’s Miami White Stubby as he calls this genotype.

 

[ClownWrangler]

From what you guys are saying, seems like abnormal size is usually associated with health issues. But does one necessarily cause the other or is inbreeding simply causing two otherwise unrelated effects?

You are correct. There are some incorrect blanket presumptions being made. For something as simple as breeding for size, you would have a large selection to choose from, so inbreeding would not be necessary, and these problems could be easily avoided through artificial selection. Inbreeding depression is a problem in captive breeding in general due to a small gene pool. It has little to nothing to do with breeding for specific traits. For example Jackson Chameleons in captivity for the most part have deformed horns due to extensive inbreeding, but they were not trying to make any sort of special breed. There are two ways to avoid this, periodically get fresh genetics from the wild or purging, a proven method of eliminating these defects through artificial selection even after extensive inbreeding. Just about every domestic cat or dog today was created this way as well as most farm animals.

 

[dennis romano]

I've been line breeding some Victorian cichlids since 1993 and they have begun to show dwarfism, but we can't tell if it is genetic or environmental (like bluegills in a farm pond).

Many/most captive bred marine fish (except clowns) are bred from F1 stock, the offspring are not raised up for future breeding, so no worries about inbreeding depression with them.

Jay

I have been breeding cichlids, both American and African for several decades. Over the years, I have found that inbreeding resulted in numerous genetic defects, e.g. curvature of the spine, deformed or missing swim bladders and "runts". I tried to produce a line of mini convicts years ago, using the runts as breeding stock. This resulted in total failure. Fry were usually deformed and were destroyed. Introducing a new partner from different stock resulted in a better batch of fry but were normal size.

 

[Stoney]

You are correct. There are some incorrect blanket presumptions being made. For something as simple as breeding for size, you would have a large selection to choose from, so inbreeding would not be necessary, and these problems could be easily avoided through artificial selection. Inbreeding depression is a problem in captive breeding in general due to a small gene pool. It has little to nothing to do with breeding for specific traits. For example Jackson Chameleons in captivity for the most part have deformed horns due to extensive inbreeding, but they were not trying to make any sort of special breed. There are two ways to avoid this, periodically get fresh genetics from the wild or purging, a proven method of eliminating these defects through artificial selection even after extensive inbreeding. Just about every domestic cat or dog today was created this way as well as most farm animals.

Exactly the kind of macro perspective I was hoping for. Always wondered how new species/variations can expand without a certain degree of inbreeding. So if there's no major obstacle to this, I guess it's just a matter of time? Maybe the stubby clownfish just need a couple dozen more generations.

 

[nicksreefs]

It’s an interesting topic. I’ve been breeding Betta fish for years and am a zoologist by education (evolutionary biologist). Captive breeding is certainly the way forward for the hobby, aquarium trade and frankly planet for many reasons outside of just selecting for desirable traits.

The key as already mentioned is the gene pool… we all know the joke about the guy who introduces you to his wife and his sister and there’s only the one woman standing next to him

There is a lot of evidence where breeding for dwarfism or other specific traits has lead to health issues. The overall appearance is as desired however due to selective breeding in a narrow gene pool deformities can become prevalent ina the resulting population (with dwarfism typically ratio of organs to overall mass)

That said nature does bring us smaller individuals where the body is perfectly proportioned eg the humunculus (in **** sapiens).

If you were to take a range of these individuals it would be perfectly possible to raise healthy natural “dwarf” individuals in a fairly short number of generations… as long as we’re not tempted to breed within generations. The same can be said for other traits such as feeding habits… coral safe angels anyone???

However even with this and taking the greatest of care it is worth being mindful of the nature of mating/evolution - you will end up with individuals which are largely like their parents in terms of geno & phenotypes however nature will combine these randomly so you’ll never quite know what you may get.

In fish as in dogs and cats frankly… I’ve got two westies who couldn’t be more different as case and point.

I’m currently building a new tank which mimics tidal action and is linked to lunar cycles to encourage breeding and do hope to end up with “semi selected” offspring so if ok will update later on this topic.