Endler's livebearers are nearly all hybrids!

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The Endler's livebearer has appeared to become a confusing hybrid. John Rundle speaks to the man who first brought us these fish.

At one time the Endler’s livebearer was known as the Endler’s guppy. Then a paper published in the journal Contributions to Zoology 2005 gave it the scientific name of Poecilia wingei, which meant the fish was a distinct species in its own right.

Last year I met the man behind the fish — Professor John A. Endler — at the Marine Biological Association of the United Kingdom laboratory where I work and he agreed to lecture on the livebearer at the Plymouth Fishkeepers’ Society.

He delivered to a packed house that included members of the British Livebearers Association, students from the University of Plymouth and my own fish society members.

The discovery

In this his first lecture to any society on the subject, he said that in 1975, while collecting in Laguna de Patos, Cumana, in north-eastern Venezuela, he found a Poecilia different to any other guppy in the area.

He also didn’t know at the time that the first person to collect it was Franklyn F. Bond in 1937.  

Water in the lake was quite hard at 27ºC/81ºF and very green with unicellular algae. This and small planktonic life represented part of the fish’s diet.

The lake, near the coastal city of Cumana is only separated from the sea by a thin strip of land. Internet accounts of the area often state the water is brackish and you will need to add salt to aquarium water to keep these fish.

Professor Endler showed satellite pictures of the lake as he knew it and then some recent pictures, revealing that the sea had now breached that strip of land and entered the lake. He said that the freshwater fish have probably not survived this geological change, but he had heard of other populations in another area.

The fish did not readily breed in his laboratory and would not cross with the wild guppies he collected. He gave a stock to Dr. Donn Eric Rosen, the then curator of ichthyology at the American Museum of Natural History who died before naming the fish.

However he had earlier passed on some to Dr. Klaus Kallman, of the New York Aquarium.   

Professor Endler said that he was totally unaware that Dr. Kallman had given the fish the common names of Endler’s livebearer and Endler’s guppy until about 1980.

Dr. Kallman then introduced it to fishkeepers in Germany. Unfortunately, it was probably around that time that it was crossed with the guppy, Poecilia reticulata. It spread throughout Europe and Professor Endler noted that the colours of original wild fish were changing.

Picture evidence

He produced photographs of male Endler’s livebearers, starting with the fish that appeared nearest in colour to the patterns of the original Venezuelan fish. These had striking gold and yellow colours on the body.

As the pictures progressed to the aquarium strains of fish the beautiful gold body colours were becoming less prominent.However, the professor said that wild Endler’s livebearers are described as polychromatic, so they can throw many different colour combinations.  

As well as metallic polychromatic patterns they usually exhibit a characteristic black band on the body — a feature separating them from the wild guppy.

He also illustrated how fish breeders have modified fin shapes and even the female of the original livebearer had a different body shape to the wild guppy. From photographs, she was a more slender fish.

He quoted a paper published in the Journal of Evolutionary Biology which showed different body shapes of separate populations of guppies and the Cumana guppy —so called as there was no scientific name for the Endler’s at this time. This indicated how shapes of the two fish had a strong influence on sexual selection between males and females.

It was also thought that the more slender shape of the Cumana guppy helped it to avoid many predators.

It’s clear that the chances of finding pure strains of Poecilia wingei are rare and some fishkeepers are searching for different colours and fin shapes. Endler says that most of the fish in the hobby are now hybrids.

Accepting this fish for just what it is…

In their 2005 paper Poeser and co-authors gave the fish the name Poecilia wingei in honour of Dr. Ojvind Winge.  

He headed the department of physiology at Carlsberg laboratory until 1956 and his work on the colour patterns and genetics of sex determination in the common guppy, provided the basis for understanding colour polymorphism among guppies.  

This does not help the fishkeeping community because I have yet to see a fish tank marked with this name. We still see it called Endler’s livebearer.

We have to admit that hobbyists have, by selective breeding methods, cut the chances of having a ‘pure strain’ but, as Professor Endler said during his talk: “Perhaps we now should just accept this little livebearer by the common name of the Endler’s livebearer and look at it as an attractive aquarium fish.”

Breeding expert

John Rundle has bred hundreds of freshwater and marine species.  He reveals here how he got on with some Endler’s:

It was quite some time before Professor Endler could get the livebearer to produce fry in his laboratory. Now of course it appears breeding is not a problem.

All the so-called Endler’s livebearers in dealer or fishkeeper tanks are not kept in the wild conditions, as described, with green water and algae missing.

I came across a tank in my local dealers with the Endler’s livebearer name tag. The male appeared to be of the colour markings quite close to those pictures I had seen of the wild fish. I could not resist them and bought three males and six females!

I housed them in a 60 x 30cm/24 x12” planted tank and they settled in and were feeding on flake food and live foods such as Grindalworm and whiteworm.

Professor Endler had not detailed actual water parameters at the original wild site but I discovered on the Internet that the ideal temperature range was 21-28ºC/70-82°, ideal pH was 6.9-9.0 and DH 7-20. My water temperature was 25ºC/77°, pH 7 and DH 6, and, according to the ideal readings, was on the soft side. However the fish did not seem too bothered.

Courtship behaviour has been compared to that of Poecilia reticulata and the male’s dance seems to involve very short, erratic, fast movements around the female. I think male guppy courtship patterns are smoother and he will chase the female fish for longer.   

Poeser, Kempes and Isbrucker’s paper details courtship behaviour and highlights a difference between Poecilia wingei and P. reticulata in the gonopodium. A structure called the gonopodial palp extends beyond the tip of the gonopodium in P. wingei, but not in P. recticulata.  

It lacks a hook at ray three and this may or may not have an influence on courtship.  

The guppy (P. reticulata) can produce fry about every 28 days while the Endler’s livebearer only takes 23-24 days between broods.

When I noticed my female Endler’s gravid in the stock tank they were removed to a separate tank with a home-made breeding trap made of plastic mesh and with a large surface area, allowing plenty of swimming space.  

In the trap were clumps of Java moss to give the fry protection before leaving for the tank, as Endler’s will eat their newborn fry if given the chance.

Females can produce a brood from about two months, but numbers can be as low as six. Mine produced about 20 each.

I fed the newborn fry live microworm in the morning and brineshrimp nauplii at night, along with crushed flake food.

Within six weeks I could define males starting to show body colour, but females can be selected earlier by the gravid spot under the belly. 

I separated the males from females as early as possible, creating some control over mating, and I was interested to see if the colours of the male babies were different than their parents. After several broods the males, when adult, were just like their original parents!

This article was first published in the December 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.