The Half-Red Hemigrammus: A New Species?

Author: Ivan Mikolji

Our South American adventurer journeys through the jungles of Venezuela to investigate the vibrant half-red Hemigrammus, a possible new tetra species for the hobby.

When you sit in front of your aquarium at home, have you ever wondered how all these plants, fish, and invertebrates entered the hobby for you to enjoy in the first place?

The Route Home

Most of the organisms in aquariums were discovered either by professionals who collected them or by astute importers who spotted them in a shipment and sent them to biologists for identification. Some of these were discovered a long time ago, such as the royal pleco Panaque nigrolineatus, which was described in 1877. Others are fairly new to science and the hobby, such as Pseudolithoxus tigris “L-257,” which was described in 2000. Some are common in the aquarium hobby but have not been described yet, such as the blue phantom pleco Hemiancistrus sp. “L-128.” And of course, there are some rare ones in the hobby that are undescribed, such as Apistogramma sp. “Caura River.”

New Species

While new species of mammals and other large animals are rarely encountered today, new species of insects and fish are still often found. My experience has been that it is not hard at all to find a new species of fish. A few months ago a biologist friend of mine, Carlos DoNascimiento, found a new species of Trichomycterus in a river in the middle of the city of Valencia, Venezuela, which is just a few miles from where I live.

As you can see, my friend didn’t have to go into the middle of a jungle to find a new fish species. On many occasions I have encountered specimens in the wild that I thought could probably be new species of freshwater fish.

Sometimes I will take a look at a fish when I get into a river and say, “Wow! This is something I have never seen before!” But once I look at an atlas or take it to a specialist, it just winds up being a known species I had never seen before or didn’t know existed.

Determining Species

Figuring out what species you have is extremely tricky when you are not an expert on a certain family of fish. For example, I had taken pictures of some Farlowella species in different rivers across Venezuela, later looking in an atlas and determining them to be Farlowella acus.

The picture in the atlas resembled the fish in the pictures I took, but once I showed my pictures to experts, they told me to bring the fish into the lab because there is no way identification could be made solely with a picture. They have to count the rays or scales because there are many Farlowella species in Venezuela that look alike, such as F. acus, F. curtirostra, F. mariaelenae, F. martini, F. odontotumulus, F. oxyrryncha, F. venezuelensis, F. taphorni, and F. vittata.

It is therefore always indispensable to know the exact location of where a fish was photographed or collected, and to be really sure of what species it is, a specialist has to look at the morphological features. Even after carefully recording the collection information and showing the fish to the experts, I still sometimes wind up finding no information about it.

Identifying a New Species

One of these fish is what I call the half-red Hemigrammus. The half-red Hemigrammus resembles—the closest match I could find, at least—Hemigrammus stictus. I spotted these half-red fish on many expeditions to the Capanaparo River National Park in the Apure State of Venezuela.

I first saw it on March 20, 2007 during an expedition with George Fear from Shark Aquarium. Because it was the first time I saw it, I 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 is determined in the scientific world or how to figure out if it was a new species or not, I decided to speak to a specialist.

My Interview with Professor Provenzano

I went to the Central University of Venezuela to interview Professor Francisco Provenzano, who is the curator at the UCV biology museum and has described (and helped to describe) many species of freshwater fish, such as Acestridium dichromum, Pseudolithoxus anthrax, and Pseudolithoxus tigris, just to name a few. His specialty is the Siluriformes (catfish) order. He also has a couple of fish named after him, such as Creagrutus provenzanoi, Lebiasina provenzanoi, and Phenacorhamdia provenzanoi.

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, using the example of the half-red stictus. When I began to tell him why I thought it was a new species, he interrupted me and said, “It is easier to look at things the opposite way around. It’s easier to start by saying why you think it’s not a stictus.”

Taking his advice, my first task was to understand what makes a stictus a stictus so it could be compared to my half-red Hemigrammus. Because I could only find vague information on the Internet, I emailed Professor Donald Taphorn of the Museo Zoologico in Venezuela for the scientific description of stictus.

Prof. Taphorn is an incredible American ichthyologist who worked with Venezuelan fish for many years. I would say he is one of the Venezuelan fish gurus.

In short time, he provided me the following: 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. The type material or original specimens were collected from Guyana’s Essequibo River drainage, and it would grow to a size of approximately 4 cm (1½ inches).

Steps to Discovery

The scientific data on the stictus allowed me to uncover some of the differences. The half-red Hemigrammus is different from a stictus because its red spot extends past the adipose fin up to the middle of the dorsal fin—it is actually half red. Another distinctive trait is that I have never seen a specimen larger than 3.5 cm (1¼ inches) in length, with the average length being 2.5 cm (1 inch).

As I have been studying this area extensively for more than two years and have been there on numerous occasions during the dry and rainy seasons, it is highly unlikely that I have not seen them as adults. 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 for them to swim, given that they are only 2- to 3.5-cm (¾- to 1¼-inches) long.

The second piece of advice Francisco Provenzano gave me was to collect the specimens in a proper way so they could be studied scientifically. The basic steps were to write down some basic info that included a description of the habitat. This had to have the exact location, name of the river, and (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 told me to collect some samples for DNA studies. You also had to note the date, the collection method (cast net or hook and line, for example), and the name of the person who collected them.

Going off to look for the samples, I started the trip at 4:30 a.m. from Valencia, Venezuela. The road trip lasted nine hours and I only stopped to get gas or a soda. By 1:30 in the afternoon, I was unloading the nets, containers, and the photography and video gear.

Collection

I began by taking pictures of the fish’s pristine habitat before I brought out a net for collection. I also took the water parameters and jotted down all of the data just as Provenzano had advised. Once everything was written down, I shot some video of them, which happened to be a much easier task than photographing them.

My camera kept focusing on the aquatic plants behind the inch-long fish, and regardless of the mode I set my camera to, it was difficult to hold focus due to their size and speed. I settled on focusing manually for complete control, but capturing the fish remained an almost impossible task as they swam against the water current. My solution was simply to go by quantity and luck—the more pictures I took, the higher my chances were of getting a fish in focus.

After taking approximately 90 pictures, I wound up with three to five decent ones. On a second expedition with George Fear and Oliver Lucanus, we collected some and took pictures of them in a small aquarium placed between two tree branches. When the fish became 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 photography session had ended, I collected some with a net and returned home.

Collection Information

Date: April 11, 2008

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

Temperature: 28.3°C (83°F)

pH: 5.2

Substrate: Yellowish sand with low silt content

Aquatic Plants: Ludwigia inclinata var. “verticillata,” Ludwigia sidioides

Collection Method: Two medium-sized aquarium hand nets

Finding the Results

A few months later, I gave the collected specimens to Carlos, a professor in the Department of Biology at the University of Carabobo and a former student of Prof. Francisco Provenzano. After asking him to take a look at the samples, he very kindly gave me the following results, which I used to compare with the stictus data.

These results allowed for a more accurate guess. Carlos said that if a larger amount of samples could be collected, all the fish having a fewer number of porous lateral line scales and red up to the middle of the dorsal fin would have sufficiently different characteristics to separate them from stictus, although they would still be closely related.

He also noted that to be really 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 and time. At the end of such an investigation, you could wind up with many different species of similar Hemigrammus from different areas.

Conclusion

At the end I realized that sometimes identifying a fish correctly is not that easy, and determining if it is 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 unknown, or at least largely unrecognized.

I frequently use scientific writings to find rare fish in the wild because they hold accurate and reliable information—these writings are treasure maps showing the locations of all the fish species that have been described and kept in our aquariums. Exporters also use these publications to collect the fish we enjoy at home, and I hope that even though this isn’t a scientific paper it will spur some collector to go after the half-red Hemigrammus and make them available to the hobby.

See the full article on TFH Digital http://www.tfhdigital.com/tfh/201003/#pg77