| Central American cichlids mean different things to different people�a pet, a breeding project, a one-fish force of destruction, or a taxonomist's nightmare. However, with their personalities, colors, and wide range of behaviors, they are certainly hard to ignore, and they continue to maintain a great popularity within the hobby. And, of course, there is the surge of interest in cichlasomine hybrids such as the flowerhorn. For this group of fish in particular, health often equates with happiness; that is to say that if one looks after the cichlid's environmental, behavioral, and nutritional needs, then disease and disorder are not that common. After all, these are rough-and-tumble hard nuts that have evolved to live in harsh environments. A Diverse Group Central America has been the site of a great deal of colonizing and evolutionary radiation of cichlids, producing piscivores such as the wolf cichlid Parachromis dovii, fry predators like Amphilophus sagittae, molluscivores like A. xiloaensis, and substrate-sifters like the firemouth Thorichthys meeki. Some are even largely vegetarian, while Vieja synspila, the firehead cichlid, is also partially frugivorous. Hence, the first step in achieving health and happiness is to select your fish appropriately by doing some research, part of which involves a look at how a particular cichlid fits into its original wild niche. Unfortunately there is a lack of information on the wild behavior of many of these fish in aquarist literature, but more is appearing all the time. One Example Let's look at an old favorite, the Jack Dempsey Archocentrus octofasciatus. Its natural range is the Atlantic slope of Central America, from Rio la Antigua in Veracruz south to Rio Ulua, Honduras (Artigas Azas 2004). It is an inhabitant of slow-flowing rivers and lagoons that are characterized by mud bottoms and limited aquatic vegetation. Water conditions are generally moderately hard with a pH of 7.5 or over, but seasonal variations do occur here, especially during the spring when water levels are low. At this time many of these water bodies are stagnant, becoming murky, very warm (34C/93F or more), and low in dissolved oxygen, and it is during this dry season that the fish spawn. Reproductively active males establish suitable territories that they defend against rivals, non-reproductively active Dempseys, and other fish, but into which they will actively entice females by display and probably pheromone dispersal. Once eggs are laid, the female guards and tends to the eggs while the male continues to defend the larger territory. Role reversal occurs after hatching, with the male tending to the larvae while the female makes forays away from the nest, possibly to refuel after her intense maternal duties. Once the fry become free-swimming, the parents take on more equal roles in guarding the young, digging pits in which to deposit the fry and stirring up food particles for them. A. octofasciatus is an omnivore that sifts around the muddy bottom of its native waters in search of anything edible, such as crustaceans, insect larvae, worms, and algae. In the confines of an aquarium it will take smaller fish, but it is by no means a specialist piscivore, and fish should not be considered a major part of its diet. Now, let's take a Jack Dempsey and transfer it into an aquarium. The main differences between this and a Honduran tributary are in water quality, diet, space, and cohabitants. Water Quality In an aquarium, water quality is, or should be, close to optimal, with extreme clarity. There should be minimal nitrogenous compounds such as ammonia, nitrite, and nitrate, high dissolved oxygen levels, and suitable pH and hardness. Temperature is properly maintained. All of these factors encourage good health, and the water clarity means that conspecifics are easily spotted. Diet The food factor can be broken down into two parts, variability and constitution. Wild diets are variable both locally and seasonally. A great deal of energy is expended just finding food. Dempseys, like most cichlids, are greedy fish reflecting an aggressive gotta-have-it attitude towards food as a survival mechanism. During the dry spring months of February to May, the warm water temperatures are likely to encourage the reproduction of many prey invertebrates, and the low water levels concentrate them. At other times of the year, food will be less plentiful and more dispersed. But now the living is easy, and the fish can rapidly gain condition, diverting excess energy into egg and sperm production. In an aquarium, however, food is offered once, twice, or maybe more times a day, every day, day in, day out. This species is omnivorous, with a high invertebrate intake, particularly crustaceans and insect larvae. Typical dietary values for shelled crustacea (such as shrimp) are a protein content of 10 to 20%, fat 1.0 to 4.0%, and fiber of 20 to 40% (most of which is chitin). We have to remember that crustaceans form only a part, albeit a major one, of the diet of A. octofasciatus, but it does start to give us ballpark figures for their dietary requirements. By contrast, typical commercial cichlid foods often have protein contents of 36 to 48%, fat levels of 4 to 10%, and fiber levels of around 2 to 4%. Space Aquaria are tiny in comparison to the native habitats of cichlids. An A. octofasciatus that decides to establish a territory will define a three-dimensional volume, basing its perimeter largely upon a number of geographic features such as rockwork, submerged branches, or even the presence of other territorial con-specifics. To avoid competition, similar species will also segregate themselves according to habitat. For example, among the cichlids in the Midas cichlid complex present in Lake Xilo�, Amphilophus xiloaensis tends to spawn and raise its young in rocky areas, A. sagittae prefers rocky/weedy environments (often over sand), while A. amarillo is found more often in aquatic vegetation. Obvious topographic features in an aquarium include rocks, driftwood, and even the glass sides themselves�detectable by the fishes' lateral lines even if not visually apparent. Because most adult male cichlids in captivity are in a constant state of reproductive activity, they readily establish and attempt to maintain a territory. For those larger cichlids that would normally dominate several square meters in the wild, the whole aquarium becomes their potential territory. Here they will await a passing female (they have no idea she might be the only one in your collection!) and attempt to drive out all other fish�particularly other cichlids (rivals for mates, real estate, and possible food resources) and catfish, which are natural predators of cichlid young. Cohabitants When not breeding, Jack Dempseys, like other Central American cichlids, are only moderately territorial, so keeping one in an aquarium with a number of individuals of different species will often work, but if we attempt to establish a breeding pair of A. octofasciatus from two adults, they must both be sexually active. Remember, the male will establish a territory first and attempt to attract a female to him. If she is not receptive, she becomes just another competitor for food and space and will be attacked and driven from the territory. If the territory is the entire tank and she cannot escape, he will kill her. Extending the Example Okay, now lets start to pull some threads together, broadening the discussion to include all Central American cichlids. The captive diet of cichlids represents the equivalent of an optimal diet both in terms of its constitution and its availability. The quality of the food is as good as, if not better than, the fish would ever encounter in the wild, and it is available all year. The excellent water quality encourages optimal growth rates. A. octofasciatus rarely reaches 20 cm (8 inches) TL in the wild but can achieve 25 cm (10 inches) in captivity (Artigas Azas 2004). Not only do aquarium fish get bigger sooner than their wild counterparts, but just like wild fish in those warm spring months of optimal foraging, they have energy to spare that allows the gonads to ripen and trigger breeding behavior. Therefore, most adult cichlids (especially the males) are in a constant state of sexual readiness in captivity, and most males will therefore attempt to establish territories. Other fish in the aquarium become targets and are mercilessly attacked in an attempt to drive them away. The victims are harassed such that they are unable to feed or move out from hiding, or worse still, they sustain injuries and develop potentially life-threatening secondary infections. Empirical Evidence Work done with tilapia (Faisal et al 1992) found that social confrontation between aggressive individuals leads to immune suppression, an effect mediated in part by naturally produced opioids that are released as part of the stress response, increasing the chance of disease and infection occurring. However not only are the other fish stressed, but so is the aggressor who, try as he might, just cannot clear his proposed territory of intruders and must expend lots of time and energy attempting to keep everyone else at bay. It is probably this stress response that allows communities of single Central American cichlids to be maintained. Provided the aquarium is large enough, living in a community of large aggressive cichlids triggers a stress response that will dampen down the production of sex hormones. Add a female, and the dynamics are likely to change; in fact, adding a sexually receptive female is likely to trigger full-blown reproductive territoriality. In the African mouthbrooder Astatotilapia burtoni, male testosterone levels were found to significantly increase within 60 minutes of exposure to female sexual steroids (Cole 2003). Common Diseases of Central American Cichlids The causative agents of the most commonly encountered maladies in these fishes are external parasites, internal parasites, and bacteria. External Parasites White Spot Ichthyophthirius multifiliis This very common and distinctive disease is caused by a protozoan parasite that afflicts freshwater fish worldwide. It has a complicated life cycle, with stages both on the fish and in the environment. Water temperature modulates the life cycle of Ichthyophthirius multifiliis�at 24 to 26C (75 to 78F) the life cycle is completed in around four days. Cichlids are usually able to mount a good immune response so that healthy fish will eventually shake off the infestation. However, cichlids that are stressed by poor water quality, constant aggression, or other factors may not be so fortunate. The associated immune suppression can allow large numbers of Ichthyophthirius cysts (which are the white spots) to establish, covering the fish look with white pin-head sized dots on its skin and fins. These cysts can cause severe damage to the gills and skin, and also allow secondary infections to invade. Infections can build up rapidly, and mortalities can occur, especially if the gills are heavily parasitized. For treatment, use a proprietary white spot remedy. Ichtyobodo necator This parasite was formerly called Costia necatrix. The first obvious signs of infection are a loss of color, with dull areas apparent on the skin because of secondary mucus production in response to the presence of the parasite. Badly affected fish lose their appetite, swim with their fins clamped, and may scrape against objects. They may wobble as they swim, even doing this on the spot. The skin becomes reddened, then hemorrhagic, and can progress to ulceration. The gills become pale and covered in thick mucus. Fungi such as Saprolegnia are common secondary invaders of lesions. Treatment: use a proprietary ectoparasitic treatment or glacial acetic acid dips at 8 ml per gallon for 30 to 45 seconds. Raising the temperature to over 30C (86F) will help to eradicate this parasite, but this will only help with species of fish able to cope with high temperatures. Depopulating aquaria for 24 to 48 hours may be useful, as the parasite can only survive off the host for a few hours. Medicate the fish in a separate treatment aquarium. Chilodonella These motile protozoa graze on epithelial (lining) cells of the gills and skin. The most significant predisposing factor is temperature�Chilodonella spp. prefer lower temperatures of 18 to 22C (64 to 72F), and outbreaks are more likely to occur when fish are exposed to the low end of their temperature tolerance. Typical signs of disease include respiratory distress, depression, clamped fins, and turbidity of the skin. The skin turbidity is due to a dramatic increase in skin mucus production in response to the irritation caused by the parasites. When affected fish are removed from the water, this mucus can form into grey gobbets of mucus. There is often an increased breathing rate�the gill covers move faster and are extended much wider in order to maximize the flow of water over the compromised gills. Infested fish may hang around at the surface or seek areas with relatively high oxygen layers, such as filter outlets. Treatment: use a proprietary ectoparasitic treatment. Also salt at 3 grams per liter until symptoms stop. Internal Parasites Spironucleus vortens is usually thought of as the cause of hole-in-the-head or head-and-lateral-line erosion (HLLE) disease in discus Symphysodon spp., but it can and does cause problems in Central American cichlids as well. Spironucleus lives in the gut, and if the fish becomes immunosuppressed, the parasite numbers build up. This parasite can cross the gut wall and spread in the bloodstream to anywhere in the body. The liver has a huge blood supply, and so it is frequently targeted in these cases. Damage to the gut wall affects the ability of the fish to digest its food, so infected fish lose weight and pass white, jelly-like feces. Less often than in discus, erosive holes can appear on the head, usually associated with the lateral line. The small pores that form the lateral line enlarge and may fuse. Often there is a whitish, stringy discharge from the pores. In some cases large areas of skin may be affected. Treatment of choice is with the antibiotic metronidazole. Dimetridazole has been used in the past, but there appear to be problems with sterility in fish once this medication has been used. Hexamita Hexamita is a protozoan that is often confused with Spironucleus. It, too, is an inhabitant of the gut whose numbers can increase if the fish are stressed. Infected fish lose their appetite and become lethargic and thin. Some fish may develop a dropsy-like condition with swelling of the body cavity. Hexamita can spread via the bloodstream causing a disseminated hexamitiasis. Less severely affected adult cichlids may experience reduced fertility, egg hatchability, and fry mortality. Treatment is with metronidazole at 50 mg per kg of body weight, added to the food daily for five days. As an alternative for fish that are not feeding, metronidazole can be administered in a bath at a concentration of 5 mg per liter every other day for a total of three treatments. Cryptobia Cryptobia iubilans is a protozoan parasite that is thought by many to be the main culprit behind Malawi Bloat, a poorly understood condition not only of Rift Lake cichlids but one that is also transmissible to Central American cichlids. It has been transferred to Thorichthys meeki and Hypsophrys nicaraguensis. The main damage caused by this parasite is that it triggers inflammatory reactions (granulomas) in the lining of the stomach, but in many cases it can spread to involve the liver, kidneys, brain, and other organs. If the liver and kidneys become involved, a buildup of fluid in the body cavity can occur, causing the bloating. However, in many cases there is no bloat; often the fish just waste away. Triggers for disease outbreaks include poor water quality, stress, and handling. In herbivorous cichlids diet almost certainly plays a role�failure to provide sufficient vegetable material in the diet may produce an altered gut environment that allows Cryptobia to cause problems. Infected fish separate themselves off, eventually becoming so anemic that they hang at the water surface. They show a high respiratory rate, and death usually occurs within 24 hours of this stage. In some collections, virtually all the cichlids will carry a low level of infection, with the disease showing itself as a low grade loss of fish over a period of time. There is no effective treatment, although antibiotics such as metronidazole appear to be useful in controlling outbreaks. Capillaria Capillaria are small roundworms that live in the cichlid's intestines. These worms compete with the host fish for nutrition and can cause gut obstructions. In addition, it is thought that these worms damage the lining of the gut, thereby allowing protozoa such as Spironucleus and Hexamita to invade the rest of the body. Infested fish lose weight, although their guts may be so impacted with worms that the abdomen appears bloated. White, stringy feces may be passed by the fish, and if these are examined microscopically, typical capillarial eggs (almost urn-shaped) will be seen. Treatment is with various anthelminthic drugs such as levamisole at 10 mg per liter as a single dose added to the water. This is particularly good for killing larval worms. Suspend carbon filtration. Piperazine at 2.5 mg per gram of feed, added to the food, is useful, but this may only kill adult worms. Another option is fenbendazole at 50 mg per kilogram of body weight added to feed, or by stomach tube if the fish is large enough. Fish are quick to refuse medicated food, so do not feed them for 24 to 48 hours prior to offering such feed. Bacterial Disease Bacterial infections are common and usually stem from wounding or from poor water quality. Large, robust specimens may heal spontaneously if separated and given optimum water conditions and food, but some may require antibiotic medication either by injection or in the food. Most Central American cichlids are very tolerant of salt water, and this can be used at a dose rate of 1 to 5 g per liter as a permanent bath, to help with osmotic balance should the cichlid have a significant skin lesion such as an ulcer. Lymphocystis Lymphocysitis is an iridoviral infection that establishes itself through the bite wounds and abrasions received during typical cichlid conflicts. More disfiguring than a serious health risk to the fish, it is usually self-limiting and will disappear of its own accord once the cichlid mounts an immune response. Typical signs of this virus are the large gray-white or yellowish cauliflower-like nodules on the fins and skin. Occasionally these growths can occur internally and cause problems, but this appears to be quite rare. The use of ultraviolet sterilization may help to reduce its spread. Black Spot Disease Anecdotally, hybrid parrot cichlids are said to occasionally succumb to "black spot disease." This disease has not yet, to my knowledge, been either identified or even confirmed. The color pattern in these fish can be variable and inconsistent, so black markings can come and go over time. Deaths suffered while fish are showing these black spots may be due to other diseases, such as Spironucleus, with the altered coloration being incidental. However, the tilapia Oreochromis mossambicus infected with one type of fish tuberculosis (Mycobacterium marinum) do develop areas of melanin concentration around inflamed areas of the skin (and in some internal organs) as part of their response to this infection, causing small black spots to appear. This does appears to be an uncommon effect. Another possibility is that it could be Plistophora (the cause of neon tetra disease) triggering melanocyte accumulations, as it appears to do in angelfish (Pterophyllum spp.). Fortunately, as I stated at the outset, most if not all of these ailments can be avoided by proper attention to the environmental, behavioral, and nutritional needs of your fish�in other words, keep them happy, and they'll stay healthy! References Artigas Azas, Juan Miguel. 2004. "Watch Out, Jack's About" Today's Fishkeeper. September 2004. PS Magazines, Ltd. Cole, Todd. 2003. Olfactory, behavioral and endocrine responses to putative steroidal pheromones in an African cichlid fish (Haplochromis burtoni). Thesis Seminar M.Sc. Department of Biological Sciences University of Alberta. Faisal M, Chiappeli F, Ahmed II, Cooper EL and Weiner H. 1992. [The role of endogenous opioids in modulation of immunosuppression in fish] [Article in German] Schriftenr Ver Wasser Boden Lufthyg 89: 785-99. Liebel, Wayne S. 2004. "The Midas Cichlid Species Complex of Nicaragua" Tropical Fish Hobbyist, July 2004. T.F.H. Publications. Sidebar: Minimizing Stress through Diet Fish that are stressed are immune compromised and therefore more susceptible to disease, and it is often the way that we keep them that leads to this immune suppression. In particular, look at the dietary preferences of your fish. By all means, use commercial pelleted and flake foods as a basis for your cichlid's diet, but supplement with a wide range of other foods. Appropriate frozen foods range, depending on which species of cichlid you are feeding, from whole fish to crustaceans (various shrimps), and from insect larvae (bloodworms, black mosquito larvae) to vegetarian diets. When provided with a more natural diet, your cichlids may not grow quite so quickly or quite so big, but they will be healthier! |
| Lance Jepson July 2005 |
| NUTRITION, HABITAT AND HEALTH OF CENTRAL AMERICAN CICHLIDS |
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