Water Conditions - Malta Aquarist Society
Transcription
Water Conditions - Malta Aquarist Society
Determining the sex of fish seems to be a very popular question. This is not always as easy or reliable as one might hope, notwithstanding, there are several techniques for determining a fish's gender. If your fish are dimorphic (i.e., males and females have distinct coloring patterns), the task will be rather easy. All you need to do is find pictures of both the male and female for your species, and then simply compare. Sometimes fish that are dimorphic have very subtle differences and distinguishing them can be difficult, and may not always be apparent. In this case, solving the mystery of gender for these fish should be addressed as if they were monomorphic (i.e., males and females look similar). Determining the gender of monomorphic species requires a process commonly called "venting“. This involves removing the fish (with wet hands) and examining their dorsal side, looking for the genital pore between their anus and anal fin. As the following two pictures will demonstrate, the more anterior pore is the anus, while the second pore is the genital papilla, or vent. The genital papilla (also called an ovipositor for females) is the pore through which the fish will excrete either eggs or milt. Male Frontosa Female Frontosa Generally speaking, females will have a larger genital papilla than their male counterparts. This larger size is needed to accommodate the passage of eggs. This difference is more difficult to distinguish for substrate egg layers (e.g., Neolamprologus spp.) because their eggs are smaller than those of female Mouthbrooders. There are other methods aquarists use to sex their cichlids, albeit less reliable. Some of these include noting behavioural differences, size differences, body and fin shape differences, as well as the presence of egg spots. Most male Mouth brooders have at least one egg spot on their anal fin, if not many more than this. Unfortunately, there are only a handful of species where males exclusively have egg spots. Many females also commonly display at least one egg spot. This fact makes relying upon the presence or absence of egg spots unreliable at best, but it can still be helpful, as males tend to have more egg spots than females of the same species. Note this is a broad generalization. Another "shotgun" method is relying upon body size, as males are often larger than females. And then with some species, particularly Lake Malawi species, fin shape is a somewhat reliable method for determining gender. Below I have posted pictures of wild pair of Auloncara hansbaenschi. A difference can be seen by looking at the most posterior portion of their dorsal fins. Males' dorsal fins end with an exaggerated point, while females' dorsal fins end with a rounded curve. The only sure way to determine the gender of your African cichlid is to examine their vent region. Unfortunately, many fish shops do not properly label the fish they sell. Often they are sold with only a common name (e.g., Red Top Zebra, Electric Blue) or even worse, in an unlabeled tank they mysteriously referred to as "Misc African cichlids". Common names are very unreliable and can vary from one supplier to the next. Scientific names (i.e., binomial latin names), on the other hand, are the only names which do not vary from one shop to the next or even between languages. Choosing the Right Size Tank Often, the size of the tank is not the optional factor, but rather, hobbyists are forced to ask, what will work in my already existing tank? Well, there are too many fish out there to go species by species, but in general, it is recommended a 55 gallon (200liter) tank as the minimal size. Smaller tanks will work for some dwarf species, Tanganyikan ShellDwellers, and Victorian Hap’s, Aquascape Many species require an aquarium aquascaped with lots of rock. Once you get the rock in your tank, you have lost much of the available swimming space and available oxygen. Plus, a smaller tank will heighten aggression, because there is less territory to claim. In general, the larger tank the better. The more water you have, the more stable their aquatic environment will be. The temperature will not fluctuate as much, nitrates will not build up as quickly, and there will be more swimming space available. Also, if you put your hands in the tank, and by accident have some toxic chemical on them, it will be less likely to harm the fish due to the dilution factor. But not all large tanks are created equal. Aquariums that are long and skiny, allowing a large water-to-air interface are best because they permit a greater amount of water oxygenation. If this value ever gets too low, your fishes's health will quickly become compromised. Aquascape Water Conditions – PH Levels pH is a measure of the acidity or alkalinity of the water, or in other words, the availability or unavailability of Hydrogen ions. What does this mean for your fish? Well, African Cichlids enjoy alkaline water conditions (i.e., pH above 7.0). pH levels vary depending upon the lake. The ranges for the three East African lakes are as follows: Lake Malawi..................7.4 - 8.6 Lake Tanganyika............7.8 - 9.0 Lake Victoria.................7.2 - 8.6 Water Conditions – PH Levels These values are approximate ranges. In nature, the pH levels will vary somewhat as the levels of the lakes will rise and fall through the years, making them either less salty or more salty. In the aquarium. African cichlids can adapt to wide ranges of pH. What you need to be mindful of is to not make any rapid adjustments to the pH level. Such a careless or unknowing act will severely shock your fish, suppressing their immune system, making them more susceptible to disease. It is recommended to keep African Cichlids at a stable pH of 8.2 8.4. Fish from all three appreciate pH levels within this range. Cichlids from West African or the rivers and streams of East African require water that is more neutral - pH 7.0. Water Conditions – Hardness The water from these lakes is very hard, containing many dissolved minerals and salts, such as Carbonate and Magnesium. If you live in an area with hard water, you may count yourself very lucky. But for those who do not, there are many easy measures you may take to make your water more alkaline and "hard." Crushed coral sand, shells, limestone, and other rocks such as slate are good at pushing the pH of the water up into the alkaline range by adding Phosphates and Calcium to the water. These alone will typically only drive the pH to 7.6, which is suitable, but not ideal. Remember that Africans can adapt to a wide range of alkaline levels. Water Conditions – Temperature The optimal temperature is 24 - 27°C. Ideally the tank is kept at a constant 25°C. High temperatures will increase a fish’s metabolism, boost their immune response, as well as stimulate aggression. So, by raising the temperature to 27°C for a fry tank, one would speed up their metabolism, causing them to eat more and grow faster, but also require more water changes. Conversely, you could lower the temperature in your tank as a means of stemming aggression. This can be helpful if you have some really nasty fish on your hands (e.g., Melanochromis auratus, Metriaclima lombardoi "Kenyi"). This is due to the fact that the number one cause of aggression among Cichlids is food-related. If they are not feeling a need to eat as often (because their metabolism has slowed), then they are less likely to be territorial and feisty Water Conditions – Water Changes No matter how good your filter is, you will eventually need to do water changes, although filters certainly help in keeping the water quality in good shape for a longer period of time. Because African cichlid setups usually lack plants, and are "crowded", the water quality can quickly deteriorate. It is suggested that 10-20% water changes every week are best. And then, if you go every other week, double that. With most setups, it is also important to vacuum the gravel. The reason for vacuuming is because waste can build up in the gravel, and anaerobic pockets can form, leading to a suboptimal condition because your aerobic bacteria can't get to it. Vacuuming these spots will prevent this situation. Water Conditions – Filtration There are so many different types of filters, not to mention all the variations on a filtration system one could devise with these. If you have a small tank (i.e., 10-35 gallon), then a simple hang on the back filter will work just fine. You want the gallons per hour (gph) flow to be 4 - 6 times the volume of your tank. So if you have a 20-gallon tank, you will want a filter that cycles 80 - 120 gph. If you have a larger tank, you will need a more sophisticated filtering system, mostly because many "hang-on-the-back" filters aren’t adequate and can’t meet the gph requirements. Substrate There are several options. Gravel, sand, crushed coral, even crushed marble or granite. There are also all sorts of color one could select for their substrate. A very popular substrate is crushed coral gravel or coral aragonite sand. The coral slowly dissolves and thereby increases the hardness of the water. It helps to stabilize the pH and the hardness of the water. Hard water, if left alone and tested a week or so later, would show a decrease in its hardness. This is because minerals, which make the water hard, don’t stay suspended for very long. Unless you use buffer, have rocks in your tank, or use crushed coral, water changes are necessary not only to reduce nitrates, but also to restore the pH and hardness of your water. Some say that crushed coral irritates the gills of cichlids, but as yet there is no conclusive data affirming this. Feeding Africans do extremely well if feed Spirulina flake, with an occasional treat of live or frozen food. Never feed them more than they can consume in 2 minutes totalled over an entire day, not 5 minutes! Cichlids have sensitive bowels and so food should be selected and fed with care so as to prevent "Bloat." Controlling Aggression As mentioned earlier the primary reason for Cichlid aggression is driven by food. You can control aggression by feeding your fish less, but more often. They are territorial because they want to stake out their own backyard garden from which to hunt and harvest. Conspecifics (i.e., similar looking fish) are seen as a threat (because if they are similar, they will compete for the same foods), and are chased off. Therefore, by having fish from a wide variety of species you can cut down on intra-species aggression. Also, by giving your fish lots of room to swim, and lots of territories to claim and caves to hide in, you can reduce inter-species aggression. This resource does not display every cichlid species. Instead, we display some of the most common African cichlid genera by showing a few examples of what fishes within each genus look like. Altolamprologus A. calvus (White) A. calvus (Black) A. compressiceps Astatotilapia A. burtoni A. latifasciata A. sp. "Thick Skin" A. jacobreibergi (Eureka) A. baenschi Aulonocara A. hansbaenschi Astatotilapia A. burtoni A. latifasciata A. sp. "Thick Skin" A. hansbaenschi A. jacobreibergi (Eureka) A. baenschi A. stuargranti (Ngara) A. Stuartgranti (Rubescens) A. steveni (Mbamba) Aulonocara Chalinochromis C. brichardi C. sp. "Ndobhoi" Copadichromis C. azureus C. borleyi C. trewavasae Copadichromis C. azureus C. borleyi C. trewavasae C. afra (Jalo Reef) C. afra (White Top) Cynotilapia C. afra (Cobue) Cyphotilapia C. sp. "North" (Burundi) C. frontosa (Kigoma) C. gibberosa (Mpimbwe) C. leptosoma (Mpulungu) C. "Leptosoma Jumbo" (Kigoma) C. gibberosa (Zaire) Cyprichromis C. leptosoma (Utinta) Cyrtocara C. moorii Iodotropheus I. sperengerae Dimidiochromis D. compressiceps D. strigatus Julidochromis J. dickfeldi J. marlieri (Burundi) J. marlieri (Gombe) Cyrtocara C. moorii Iodotropheus I. sperengerae Dimidiochromis D. compressiceps D. strigatus Julidochromis J. dickfeldi J. marlieri (Burundi) J. marlieri (Gombe)