What is a Limia?

by Mike Hellweg, CFN (Certifiable Fish Nut)

Since we have chosen to support the Lake Miragoâne Limia project at Oklahoma University with our MASI Challenge for 2022, it is a good time to take a look at what exactly are Limias. Many authors do not support the genus Limia at full generic status currently, but for the purposes of this article, we will. I’ll go into the differences below.

The Limias are a group of about 23 species of Poeciliid livebearing fishes endemic to several Caribbean islands in the Greater Antilles. A single species each is found on Cuba (L. vittata), Grand Cayman (L. caymanensis) and Jamaica (L. melanogaster). But the real hotbed of their evolution is the Island of Hispaniola, where at least 20 species have been found! Hispaniola is divided into French speaking Haiti on the western end of the island and the Spanish speaking Dominican Republic on the eastern side of the island. Haiti is home to at least 13 species, with five found in rivers and streams (Limia melanonotata, L. ornata, L. pauciradiata, L. rivasi, and L. tridens) and the rest found in one of the largest freshwater lakes in the Caribbean, Lake Miragoâne (Limia fuscomaculata, L. garnieri, L. grossidens, L. immaculata, L. islai, L. mandibularis, L. miragoanensis, and L. nigrofasciata). It’s like a miniature livebearing version of the Cichlid species flock in the Great Lakes of Africa. With so many species found in one place, it’s easy to see why the folks at Oklahoma University want to study them and find out more about them. Finally, at least seven species are found on the Dominican side of Hispaniola (Limia dominicensis, L. montana, L. perugiae, L. sulphuraphila, L. versicolor, L. yaguajali, and L. zonata). I say “at least” as there still may be a few species yet to be described. Hobbyists are aware of at least one more “variant” or distinct population of the so-called Tiger Limia, and there may be more that have yet to be found.

Limias are similar to their Poeciliid cousins, the mollies. In fact, some hobbyists call them the “Island Mollies”, but there are differences. In general, the Limias are overall smaller than many of the mollies, with the largest Limias (Limia nigrofasciata, L. perugiae, and L. vittata) topping out at about two and a half inches to three inches and the largest mollies (Poecilia velifera, P. petenensis, P. mexicanus and P. latipinna) topping out at nearly double that. Teeth in some species are very different as well. So different, in fact, that some authors previously proposed a separate genus, Odontolimia , for some of them. Before DNA testing was available, scientists often differentiated Poeciliid livebearer species based on tooth structures and on differences in the reproductive structures of the male’s anal fin which is known as the gonopodium. In Limia there are no spines on the subdistal ray segments next to the palp (the soft, fleshy part of the gonopodium) while in Poecilia mollies there are several spines on these same ray segments.

The mollies are found on the mainland of North, Central and South America from the Carolinas in the north, along the U.S. coastline through Mexico and Central America to Colombia and Venezuela in northern South America, while the Limias, as mentioned earlier, are found only on some of the islands of the Greater Antilles in the Caribbean Sea.

by Staff Writers ‒ www.liveaquaria

Reprinted from the May 2018 Raleigh Aquarium Society Newsletter Vol 37 Issue 5

Assorted aquatic-related artIcles obtained from various sources.

Material presented is public use or copyrighted by author/organization and is listed when available.

Reprinted here from the Brooklyn Aquarium Society’s Aquatica, Volume 32, number 2 Nov/Dec 2018

Stress is present in the lives of all living things and is the force that brings about physical change and adjustment. Small amounts of stress can be harmless, or even beneficial, but high levels of stress or prolonged periods of low stress can create severe health problems. Many people are aware of stress in their own lives and can name many of the causes as well as possible treatments. However, the stress that affects fish is different and much more widespread. The nature of keeping aquatic species in confined environments generates many stresses that are unique to aquarium fish. To be successful in keeping healthy aquarium fish, you need to know what causes stress in fish as well as how to prevent it. Elevated stress levels are at the root of most health problems in fish.

Stress is any condition that causes physical or mental discomfort that results in the release of stress-related hormones or results in specific physiological responses. Stressful events will cause an increase in heart rate, blood pressure, blood sugar, and the release of cortisol. Stress can be physical, psychological, or environmental. Stress can either be short and sudden, or long and chronic. Mild short-term stress has few effects, but severe long-term stress leads to illness or death.

Short-term stress will cause an increase in heart rate, blood pressure, and respiration. The fish is reacting much as we do with the fight or flight mode. Fish can only maintain these altered states for a short period of time and then they will adapt or the stress will become chronic. Stress is accompanied by the release of the hormone cortisol, which is responsible for many of the negative health effects associated with stress. In addition to having a negative effect on growth, reproduction, and digestion, chronic stress will also lower the ability of the immune system to respond effectively and fully. This lowered immune response is what allows parasites, bacteria, and fungi to infect a stressed fish. Depending on the duration of the stress and its type of treatment, it can lead to illness or death.

There are dozens of potential stresses to fish, but common causes are:

• Elevated ammonia

• Elevated nitrate

• Improper pH level

• Fluctuations in temperature

• Low oxygen levels

• Harassment from other fish

• Lack of hiding places

• Improper nutrition

• Inadequate tank size

• Overstocking of tank

• Medications and water treatments

• Improper salinity

Elevated levels of ammonia, nitrite, and nitrate all create deterioration in fish health due to stress. High levels can cause severe stress, whereas slightly elevated levels can contribute to chronic stress. pH levels that change abruptly cause acute stress and continually elevated or lowered pH levels can cause chronic stress. Many fish adapt to long-term changes, but there are limits. pH changes of more than 1.5 points below or above recommended levels are going to have a negative effect over time and should never be considered acceptable.

Temperature fluctuations are a much underappreciated stressor of fish. Most tropical freshwater and marine fish do not tolerate temperature changes very well. Many tanks that are not set up properly will have over the recommended maximum of one degree of temperature fluctuation in a 24-hour period due to room temperature, lights, and equipment. The daily fluctuations will create chronic stress as will having a too low or too high temperature in the tank for the species of fish present. Wild fish live within very specific salinity levels (levels of salt in the water). Their bodies work hard to maintain the osmotic gradient between themselves and their environment. If their environmental salinity is not specific to their needs and is not held at a steady level, they have to work harder to maintain their osmotic gradient, which generates chronic stress. Oxygen levels that are below recommended levels can cause fish to 'breathe' faster than optimum and this can result in chronic stress. Obviously, very low oxygen levels can lead to severe short-term stress and death.

Harassment from other fish and lack of hiding spaces go hand in hand. There should be two suitable hiding spaces for every fish in the tank, otherwise there are going to be fish that are stressed and bullied. Remember that, unlike their environment in the wild, these fish are confined and cannot get away from aggressors. Aggression is a very real problem in many tanks that leads to many injuries, infections, and death. Overstocking of the tank is a common problem that contributes to almost all of the stresses in the above list, from water pollution to oxygen depletion to harassment.

Do not overstock your tanks. If you want to stress your fish, put too many in the tank and it will happen every time.

If you add something to the water to treat a disease or water condition, be aware that it can be stressful to your fish. Try to avoid treating the water if at all possible and always use a quarantine or treatment tank. Copper is an excellent treatment for ich or velvet, but it can be toxic and stressful to fish. Of course, using it is much better than letting a fish die from velvet, but it should never be used in a tank with healthy fish.

While it is impossible to eliminate all stress, we have the ability to limit or prevent many of the causes. Acute stress is more obvious and needs to be addressed very quickly. Chronic stress is often not visible. It can take weeks and months to develop. Your fish may appear to be doing fine, until one day one gets sick and dies, and then a few weeks later another one does and so on.

If you have fish that are getting sick and dying, there is probably a source of stress on them that needs to be identified and remedied.

The other big source of stress is bringing new fish into your aquarium. Buy only from the most reputable sources that move the fish in the most careful and humane manner. Acclimate your new fish properly, use a quarantine tank, and make sure your new fish are fed appropriately. Spend extra time on the new fish and be as careful as you can. Taking a little time here can make all the difference in breaking the chronic stress cycle and keeping these fish healthy and disease free. Stress is one of the most critical factors in fish health. Only by understanding the effects that stress has on fish, as well as being able to identify and prevent common stresses, can we eliminate this problem.

As aquarists, we need to be responsible for the health and welfare of all of our fish. Provide the highest quality water, nutrition, and suitable tank environment. Introduce new fish carefully and always use a quarantine or treatment tank when necessary. If we work hard to reduce the stress in our fish, we can virtually eliminate disease and health problems in our aquarium.

So long, Elliot — and thanks for all the fishy tales!

“Legendary Aquarists: Winston Churchill” by Joseph Ferdenzi

“Some Aquarium Firsts: Silicone and Power Filters” by Joseph Ferdenzi

‟Memories Are Made Of This” by Susan Priest................................................................................

“Breeding Nothobranchius guentheri” by Joseph Ferdenzi

“Keeping Limia tridens” by Dan Radebaugh ....................................................................................

“Girardinus metallicus, the Black Chin Livebearer” by Dan Radebaugh..........................................04/11

“Greater City in the Early Aquarium Magazines” by Joseph Ferdenzi

“The Origin of Modern Aquarium Series III” by Joseph Ferdenzi

“Thoughts and Opinions on Feeding” by Rosario LaCorte................................................................04/19

“Thoughts and Opinions on Feeding” Part Two, by Rosario LaCorte................................................05/17

“Modern Aquarium -- 100 Issues” by Warren Feuer

WET LEAVES: “Theatres of Glass,” by Susan Priest ....................................................................05/15

“Carpy Diem! - Part II: The Fantastic Four” by Dan Radebaugh.....................................................06/14

“The Fish From Bung Borapet Swamp: Rasbora borapetensisˮ by Alexander A. Priest................

“The Bobbeh Meiseh” by Eliot Oshins ..............................................................................................08/16

‟My Trip To Madagascar” by Susan Priest.........................................................................................09/16

“The Origin of the Greater City Aquarium Society” by Joseph Ferdenzi...........................................10/15

“A History of the Greater City Aquarium Society” by Joseph Ferdenzi............................................10/19

“Mermaid Tales: Fossochromis rostratus” Review by Sharon Barnett.............................................11/12

“A Greater City Memoir” by Joseph Ferdenzi....................................................................................11/13

WET LEAVES: “The 100 Best Freshwater Nano Species” Review by Susan Priest ...................05/15

“Ein? Swai? Tra? Basa?” by Dan Radebaugh.....................................................................................11/19

WET LEAVES: “The Ocean At Home” Review by Susan Priest .................................................12/14

MARINE FISH & FISHKEEPING

“My Saltwater Odyssey” by Patricia Radebaugh...............................................................................05/09

“Friends Don’t Give Friends These (Diseases) Plants” by Justin Warnock & Gary Lange