Half-Red tetra Hemigrammus sp aff stictus | Mikolji

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Half-Red tetra Hemigrammus sp aff stictus

By Ivan Mikolji / 2009

 

When you sit in front of your aquarium at home, have you ever wondered how all these plants, fish or invertebrates got to the aquarium hobby for you to enjoy, in the first place? If you have a freshwater or a saltwater aquarium, most of the living organisms that are in it have followed a pattern to be able to be enjoyed by us in our tanks.

 

Most of the aquatic organisms that we enjoy in our houses today have been found by investigators, botanists, biologists, explorers, etc. which get the chance to collect these specimens in the wild. Some fish get shipped by “accident” mixed with other fish by exporters all around the world. Once at their final destinations, some wind up being picked out or spotted by the importers and sent to biologists for identification. Some of these have been “discovered” a long time ago as the Panaque nigrolineatus commonly called the Royal Pleco, which was described in 1877. Some are pretty new to science or the aquarium hobby as thePseudolithoxus tigris, known as the L-257 pleco which was described in the year 2000. Some are old to the aquarium hobby but have not been described yet as theHemiancistrussp., L-128 blue phantom pleco. Some are quite rare in the aquarium hobby and have not been described yet as the Apistogramma sp. Caura River.

 

Anyways, as “new un-described” mammals and other large animals are getting quite scarce, fish and insects are the usual “new species” in science. In my point of view it is not hard to find a new species of fish. A few months ago, a biologist friend of mine called Carlos DoNascimiento, found a new species of Trichomycterus in a river in the middle of the city of Valencia, Venezuela, a few miles from where I live! This City, has more than three million people in population, so as you can see, my friend didn’t have to go to the middle of the jungle to find a new species of fish. In many occasions I have encountered some specimens in the wild which could probably be a new species of freshwater fish.

 

 

Sometimes I take a look at a fish when I get into a river and say “WOW! This is something I have never seen before!” Once I look at an atlas, or take it to a specialist, some of them wind up being a common species which I had never seen before, or didn’t know excised. This is extremely tricky when you are not a real true expert to a certain family of fish. For example, I have taken pictures of some Farlowella in many different rivers across Venezuela, I later look at an atlas and I immediately say “it’s a Farlowella acus”, which is the picture in the atlas that resembles the fish in the pictures I took, but once I show my pictures to an expert, they tell me “bring the fish in the lab, there is no way we can identify it by a picture, we have to count the rays or its scales because in Venezuela you have all these Farlowella species which look alike: Farlowella acus, Farlowella curtirostra, Farlowella mariaelenae, Farlowella martini, Farlowella odontotumulus, Farlowella oxyrryncha, Farlowella venezuelensis, Farlowella taphorni, and Farlowella vittata”. So it’s always indispensable to know the exact location of where the fish was photographed or collected and to be really sure, a specialist has to look at its morphological features. However, some fish do not pass that test and after much research, or showing them to the experts, I always wind up finding no information about it.

 

One of these fish is what I call the half red Hemigrammus. This half red Hemigrammus resembles, or the closest match I could find was a Hemigrammus stictus. I had spotted these half red fish in many expeditions, to the Capanaparo River National Park area in the Apure State of Venezuela. The first time I saw it was on March 20th 2007 on an expedition with George Fear from Shark Aquarium. Since I saw it for the first time, I have always thought it could be a new species or at least a segregated population of stictus with a distinctive color pattern.

 

As I didn’t have the sufficient knowledge of how a new species comes to life in the scientific world or how to proceed to know if it was a new species or not, I decided to speak to a specialist.

 

 

I went to the Central University of Venezuela and got an interview with Prof. Francisco Provenzano. Provenzano is the Curator of the UCV fish collection, has described and help describe many species of freshwater fish as the Acestridium dichromum, Pseudolithoxus anthrax, and the Pseudolithoxus tigris just to name a few. His specialty is the Siluriformes (catfish) Order. He also has a couple of fish dedicated after him as the Creagrutus provenzanoi, Lebiasina provenzanoi, and the Phenacorhamdia provenzanoi, just to name a few. Provenzano kindly took some time off to answer some of my questions. My first question was if it was hard to know if a fish was a new species. I set the example of the half red stictus. I told him that I thought it was a new species because… and he interrupted me and said, “it easier to look at things the opposite way around; it’s easier to start by saying why you think it’s not a stictus.”

 

So, my first task was to know what makes a stictus a stictus to be able to compare it to my Half Red Hemigrammus. As I only found vague information on the internet I emailed Prof. Donald Taphorn and asked him for the stictus scientific description. Prof. Taphorn is an incredible American ichthyologist which worked with Venezuelan fish for many years. I would say he is one of the Venezuelan fish Gurus. Not even half an hour later, he sent me the information, and this is a little description of what he sent me. Hemigrammus stictus was described by Durbin in 1909. Durbin described it as having a red spot on the caudal peduncle (between the caudal fin and the body) up to a level with the front of the adipose fin. It also stated that the type material or original specimens were collected from Guyana, in the Essequibo River drainage and that it would grow to a size of approximately 4 cm.

 

Knowing the scientific data on the stictus made it possible for me to name some differences. The Half red Hemigrammus is different from a stictus by having its red spot extend past the adipose fin up to the middle of the dorsal fin. It is actually half red and another distinctive trait is that I have never seen a specimen of more than 3.5 cm. in length being the average length 2.5 cm.. As I have been studding this area extensively for more than two years, and have been there in numerous occasions in the dry and rainy seasons, it rules out that I have not seen them in their adult phase. The other difference was the location; the state of Apure in Venezuela is very far away (more than 1000 miles) from Guyana or the Essequibo River drainage. The stictus type locality seemed too far away if you have to swim, and you are only 2 to 3.5 cm long!

 

The second step Francisco Provenzano told me to take was to collect the specimens in a proper way to be able to be studied scientifically. The basic steps were to write down on a piece of paper some basic info which had to include a description of the habitat. This had to have the exact location, name of the river, if possible the temperature, pH, conductivity, substrate type (clay, sand or rocks) types of aquatic plants found in the same spot, and current speed, or a qualitative approximation of it. He also told me to collect them and immediately place the samples “alive” in airtight containers filled with a 10% solution of formaldehyde and some in another container with ethanol at 100% for DNA studies. He also told me that the containers had to be sufficiently wide and tall to allow the samples to be fixed straight, so they were not compressed with each other or against the wall of the container. Two solutions are used because the formaldehyde is the best preservative solution, but because there is still no way of getting DNA samples from something that has been preserved in formaldehyde, ethanol is used for this other purpose. Then you had to write down on the same piece of paper, the date, the collection method, for example, cast net or by hook and line and the name of the person that collected them.

 

So, off I went to look for the samples. As usual, I started the trip at 4:30 am from the city of Valencia, Venezuela. The road trip lasted 9 hours only stopping to get gas or a soda. At 1:30 in the afternoon I was already unloading the, nets, containers, fixing solutions and the photographic and video gear. I started off by taking pictures of its pristine habitat outside of the water, before I stirred things up with a net to collect them. At this moment I also took the water parameters and started writing down all of the data on a sheet of paper just as Provenzano told me. Once I wrote all down I shot some video of them which is a much easier task than photographing them. The photo camera always wants to focus on the aquatic plants behind them instead of on the one inch fish! Even placed on macro mode, it is very unusual for the camera to read your mind and focus on the little fish. Manual focus on small fast moving fish swimming against the water current is an almost impossible task too. So my solution is always to go by quantity and luck. The higher number of pictures I take, the more chances of getting a fish in focus! So after taking approximately 90 pictures I wound up with 3 to 5 decent pictures. On a second expedition with George Fear and Oliver Lucanus, we collected them and took pictures of them in a small aquarium placed in between two tree branches. As the fish got stressed they started to lose the intensity of the red pattern, but not completely, it was still visible but less pronounced.

 

After the video and photographic session had ended I collected some with a fish net. Because they are so small I decided to fix them in test tubes. I placed four of them in a test tube full of ethanol 100% and four in Formaldehyde at 10%. This part is always the ugly part in which an animal gets killed in the name of science. Next day I drove 9 hours back home.

 

The paper I wrote at the river contained this data:

Date: April 11th 2008

Locality: Venezuela, Apure State, Cinaruco Capanaparo National Park, Caño La Pica, Tributary of the Capanaparo River.

Temperature: 28.3 c.

pH: 5.2

Iron Content: Less than 1

Substrate: Yellowish sand, less than 10/30 mesh in size, with low silt content.

Aquatic plants: Ludwigia inclinata (variety: verticillata), Ludwigia sedoides

Collection Method: 2 Medium aquarium hand nets.

Name of the collector: Ivan Mikolji

 

A few months later, I gave the collected specimens to Carlos DoNascimiento who is a professor of the Department of Biology of the University of Carabobo and was a former student of Prof. Francisco Provenzano and asked him to take a look at the samples. He very kindly gave me these results which I used to compare them with the stictus data.

 

 

Dorsal Rays

Anal Rays

Lateral Scales

Lateral Line Scales

Transverse Scales Above Lateral Line

Transverse Scales Below Lateral Line

Predorsal Scales

Internal Premaxillary

teeth

External Premaxillary

teeth

Maxillary Teeth

Half Red Hemigrammus

 

11

25

33

9

6

4

10

5

2

2

Hemigrammus stictus

11

26-31

33-35

15

6

4

9-11

5

2-3

2

 

With these results we could make a more accurate guess. Carlos DoNascimiento told me that if a larger amount of samples could be collected and if they all had a constant of less number of porous lateral line scales and the same constant in having red up to the middle of the dorsal fin, it would have sufficient characteristics as to make it a different species than stictus, but closely related to it. He also told me that to really be sure if it’s a new species, it would be useful to collect or compare them with other “stictus forms” from all the big tributaries from Apure to the Essequibo drainage. In my opinion, collecting this type of fish from Apure to Guyana for more than 1000 miles seems like a lot of work, for a long time. At the end of such an investigation you could wind up with many different species of similar Hemigrammus from different areas.

 

At the end, I understood that sometimes identifying a fish correctly is not that easy, and making it a new species is even harder. The time and effort that all these people have put into all the scientific investigations around the world is enormous and in the aquarium hobby, it’s almost unrecognized or unknown. I frequently use these scientific writings to find rare fish in the wild. Because they hold accurate reliable information, these writings are the “treasure maps” that show the X locations to all the fish species which have been described and we keep in our aquariums. All these publications let people get to, and collect the fish that we enjoy at home. I’m sure that after this article is published, somebody is going to use it to collect the Half Red Hemigrammus and make them available to the aquarium hobby.

 

This article has been published at:
• Tropical Fish Hobbyist Magazine - March 2010

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