Leather (scaleless) goldfish

Leather (scale-less goldfish)

(sketch added and updated 10 March 2009)

This blog is created to answer Norm’s question about why the leather goldfish are finless and to document what I actually experienced back in the 1990s.

See link:

http://www.goldfishkeepers.com/forum/showthread.php?t=446

In this blog, I explain further my experiences with leather (scale-less) goldfish. I have only observed them once back in early 1990s and have purchased one of them and kept it for about half a year.

In a retailer at Swanston Street pet shop in Melbourne (the business closed after 2-3 years…), in a tank full of common/comet goldfish comprising normal metallic (self-coloured red and orange and part-red and white) were also many scale-less goldfish specimens which were all deformed. As for scale-less, I do not mean matts or shubunkins, as both matts and shubunkins are fully scaled but have transparent scales. Instead, these scale-less goldfish are really devoid of scales and are true leather goldfish. They are metallic fish (although without scales), as they have silver reflecting tissue in their operculum (both sides) and not transparent (pink) operculum as true matts do. Furthermore, they do not have ‘button’ eyes. They have full silver reflecting tissue surrounding their black pupils. They were not mottled either, so they were not nacreous (calico) fishes. Furthermore, no matts or nacreous scales have ever appear in Linear or Scattered scale types in Australia to date, nor have they appear in double-tail specimens (only single-tailed), whether they are metallic, nacreous or matts. I presume no one is bothered to breed these features to matts and nacreous, as ‘mirror scales’, as they are commonly called, are so common in Australia, and appear best in metallic (and not non-shiny nacresous or matts) and best in long wild type goldfish body type as opposed to the short-bodied fantails.

If you have seen linear scale goldfish (commonly referred to in Australia as mirror-scales), then the leather scale goldfish looks like the ‘window’ regions ONLY of the metallic Linear goldfish, ie, the back below the dorsal fin and the abdominal regions above the ventral and pectoral fins. These two regions of the Linear scaled are where they are free of scales (the large scales only appearing along the lateral line).

The likely reason for the rarity of the leather goldfish appearing in retail aquarium outlets in Australia (apart from genetics, which I will discuss later) may be contributed by the fact that such deformed specimens would not normally be offered for sale, and as best they are offered instead as ‘seconds’. In Australia, few coloured ‘seconds’ are ever sold in retail aquarium stores, ie, colourful fish with deformed dorsal/tails or missing an eye or gill-plate etc. These deformed fish do not generally make it to the public, stores do not devote their precious space/tanks in their stores for selling such low demand/cheap fishes. Instead, cheap uncoloured metallic goldfish are sold as ‘feeders’ and they are generally comets/fantails of bronze wild colour. These bronze fish in Australia are not deformed, they are just un-coloured.

On closer inspection, all these leather specimens in that tank have caudal (tail) fin only. The caudal fin in the specimen I purchased and owned was not perfect in the sense that it had few soft rays and the fins ribs were not smoothly (parabolic) curved but have sharp turns (ie, a bit like regenerated damage fins which are not perfect). My leather specimen, if it was a normal metallic fish, should have been a metallic fish of the comet type. The deformed caudal rays make the two tail lobes curve inwards to each other (a bit like a lyretail molly but more so). See sketch on top of this blog of my leather specimen.

Back in the early 1990s was days before I have a digital camera, and normal point and shoot film camera just can’t take picture of my goldfish close-up. Nor did I realise how rare it is … I would have gone and get some formalin and preserve the fish when it died.

The rest of the fins for the leather goldfish were all absent with the exception of remnant stubs where the fins should have been located. Despite the deformities, these leather goldfish specimens do thrive and flourish. However, they do swim with difficulties and with an uneven keel but being born with the defects, they do accommodate their limitations/conditions. They swim with an ‘unstable’ motion, ie, waving from side to side, but they always manage to correct themselves if they are overturned during their motions in the water, ie, they don’t swim belly-up.

I decided to buy one such a leather fish and chose one of the less robust leather ones from the pet shop to see if I can keep it alive despite of its deformities. Some of the leather specimens are actually quite robust in size despite they are deformed, ie, shape like stocky hibuna. The one I chose was a slender part-red and white fish instead (out of pity). This leather fish was kept in a 2 feet tank with my other common/fantail goldfish. Apart from flakes, I fed it raw fish/prawn pieces by sticking the morsels through a toothpick and specially feed it to it when it comes to the surface for feeding. This leather goldfish learnt to feed from the toothpick eventually, but it was not easy for it to swallow (probably lack of pharyngeal teeth – see below). Otherwise, this leather specimen had no hope of competing for the food against the able-bodied goldfish in my tank (apart from flakes which got disbursed everywhere by the water filter). By hand-rearing, my Leather actually fatten-up and the caudal fin grew longer when I have the time to feed it but after about half a year, due to lack of time and care, my Leather fish got ill and die. I just don’t have the room to devote an aquarium to it by itself. I was also too young to realise the value of this fish, being a scaleless goldfish (given Linear and Scattered goldfish are so common in Australia) as a teenager. Nor do I realise I have not seen any Leather goldfish since…

My postulation of leather (finless) genetics

First of all, I am not a geneticist, but have real keen interest in aquarium fish genetics, esp Puntius barbs (being a lawyer and chartered accountant by occupation instead). I will borrow the existing knowledge about European carp (Cyprinus carpio) scale genetic studies to postulate the finless condition in leather goldfish and I am not going to go into this blog whether goldfish (Carassius auratus) and carp hybrid are fertile as opposed to sterile (subject of another blog if I have the time) and argue whether the goldfish scale mutants in Australia are hybrids (they don’t have any barbels and they don’t shape like carps, they look just like normal goldfish apart from the scales).

Although there are reports of such carp x goldfish crosses being fertile (see Trautman, MB (1957). Fishes of Ohio, with illustrated keys. Ohio State Univ Press 683 pp), however on the whole from what I have read that crosses from Japanese cyprinus carp species with goldfish are sterile (can’t remember the name and the Japanese author, it was a brilliant, small pocket size book with many pages at CAE Library), and Canadian researchers have also expressed such crosses of their strains appear to be sterile (see Jane Taylor & Robin Mahon (1977), Hybridization of Cyprinus carpio and Carassius auratus, the first two exotic species in the lower Laurentian Great Lakes, Environmental Biology of Fishes, Vol 1, No. 2 pp 205-208). Furthermore, the creator of Butterfly kois in the US, Mr Lefevre, in his website clearly communicated such crosses between carp and goldfish are sterile.

See link:

http://www.blueridgekoi.com/The-Origins-of-Butterfly-Koi-a-1.html

NB) It is possible that particular strains of c carpio may yield fertile hybrids when crossed with the goldfish, but none of the Australian scientific research of such hybrids in Australia has conclusively proved this point which I am aware of.

So, I am assuming that these Linear (Lin), scattered (St) and Leather (Leath) scale mutations arose in the goldfish independently and not crosses from the carp, as they are fully fertile.

These goldfish Linear scale mutants in Australia are also not female only. I don’t have a pond or the room to raise goldfish as a teenager back in the 1990s with only two fish tanks, ice-cream containers and a plastic tub at my disposal. The one I crossed happened to be a female Linear scale (she was already loaded with eggs when I purchased her and spawned in the bladderwort days later with the newly acquired male shubunkin when I purchased them together and it was fully fertile (discussed in my earlier blog). Of the few frys out of many which I managed to raise to maturity (also being my first goldfish breeding attempt), I only saw one metallic Linear fry, the rest were normal metallic, 2 pink matts with some orange and the rest were nacreous but not pretty as the demelanisation gene on the metallic Linear scale female parent acted on the fry, so the frys did not have the nice black speckles and multi-colour of the male shubunkin parent).

Due to the lack of genetic studies to date on goldfish scale mutants (let alone recognising and accepting their actual existence). Nevertheless, we can borrow the genetic literature to date of such similar scale mutant occurrences in the carp to postulate why the leather carp are finless.

Back in the 1990s, I have read a green-cover book from Springer-Verlag, details below:
Uniform Title Geneticheskie osnovy selektsii ryb. English

Title Genetic bases of fish selection / V.S. Kirpichnikov ; translated by G.G. Gause.

Author Kirpichnikov, Valentin Sergeevich.

Published Berlin ; New York : Springer-Verlag, 1981.


See also a link of another one of his articles online:

http://www.fao.org/docrep/005/b3310e/b3310e14.htm

Kirpichnikov from the USSR studied the scale mutations in European carp Cyprinus carpio and he has provided notations to diffrentiate each type of scale which I have borrowed in my earlier blog about Linear (mirror-scales) on 22 February 2009:


Scale Type = Symbol = Genotypes
Scaled = Sc = SSnn, Ssnn
Scattered = St = ssnn
Linear = Lin = SSNn, SsNn
Leather = Leath = ssNn

Genotype S gene controls scaliness (S = scaliness), n gene modifies the scale pattern (n = nude)

He has also identified in his book (as well as in Table 2 of the article provided in the link) that (in brief) that there are defects with Scattered, Linear and Leather scaled specimens (and progressively so from scattered to Leather). The mutants (with or without the S or N genes) suffer adverse physiological effects (called pleiotropic effects), ie, lower viability and body size in depressed conditions, have lower tolerance of heat and low oxygen environment due to less red blood cells and less rows of pharyngeal teeth (carp fish equivalent to ‘teeth’).

The important thing to draw out from Table 2 of the link is that the mutants, ie, Scattered, Linear and in particular Leather carp specimens have less rays and less soft rays overall and have much lower regenerative capacity of fins. That is, leather carp have smaller fins in general and the fins have less fin ribs and soft fin rays overall when compared to the normal scaled carp.

On the basis what is observed above in carp genotypes is also observed in goldfish in the same fashion, then I postulate that the reason why all the leather goldfish I saw in that tank were finless other than the caudal fin is that on the basis that the lack of S and/or N genes in the Leather in that particular genotype order ssNn, that this adverse effect when being expressed in the goldfish BECOMES much more aggressive than in the carp, ie, instead of reduced rays and soft rays, they simply atrophied and disappear to remnant stubs where they should be, and leaving them with a reduced and deformed caudal fin with less and deformed fin rays overall.

I have found photos of specimens of deformed Tilapia aurea which resemble my deformed leather goldfish a lot, see Figure 3.6, in particular specimen n of Fig 3.6 on page 68 of Douglas Tave's book (1986), Genetics for Fish Hatchery Managers, AVI Publishing Company, Inc., Westport Conneticut (or see Tave D, Bartels, JE & Smitherman, RO, 1983, Saddleback: a dominant, lethal gene in Sarotherodon aureus (Steindacher) (=Tilapia aurea), J. Fish Dis. 6, p 59-73).

Tave's research also noted that the S allele (allele means any of the alternative forms of a gene that may occur at a given locus) in Tilapia aurea, the S gene in its heterozygous state produces the 'saddleback' feature, ie, which is an abnormal dorsal fin. He said this S expression is highly variable on the pleiotopic effects, ranging from saddlebacks that lack only the first spine to individuals that have no dorsal fins. That is, vertebral anomalies in vertebrae 1, 2 and 3, abnormal pelvic, petoral, or anal fins, skeletal abnormalities in the pectoral and pelvic girdles. Figure 3.6 shows the range of deformed T aurea also thrive and flourish despite lacking dorsal, reduced pectoral and ventral & no anal fins.

Therefore, it appears that the leather goldfish might be suffering from pleitropic effects, resulting in the finless specimens I have observed.

Can the Leather (scaleless) goldfish be recreated again?

I certainly hope so, on the basis that Leather goldfish genotype mirrors the carp above, denoted by ssNn, then the best chance of recreating the Leather, so I can see it again is by crossing a scattered goldfish with a Linear goldfish (see item 6, Table 1 of the link of Kirpichnikov’s article). By combining the Scattered and Linear genotypes, if luck would have it that you have the right genotype order (ssNn) when crossing the Scattered (St) x Linear (Lin) (SSNn or SsNn), resulting in the preferred combination of:

St (Scattered) x Lin (Linear)
25% Scaled
25% Scattered
25% Linear
25% Leather

Instead of (bummer…):
50% Scaled
50% Linear

Well, hopefully, if time and especially LUCK permits, I’ll or I really hope someone else can recreate the Leather goldfish, take a digital photo and prove what I actually witnessed and kept once. After all, the leather sheen on a leather goldfish is quite beautiful, despite their physical deformities. Also, someone may overcome the finless effect by introducing new genes. After all, goldfish have a few races, though most of what we see today came from one of two groups of Chinese goldfish strain.

See Journal article:
An evolutionary origin and selection process of goldfish

Tomoyoshi Komiyama, Hiroyuki Kobayashi, Yoshio Tateno, Hidetoshi Inoko, Takashi Gojobori, Kazuho Ikeo

Gene 430 (2009) p 5–11


© 9 March 2009 Bill L



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