Friday, May 14, 2010

African Rift Lakes

The African Rift Lakes refer to three major lakes in eastern Africa, specifically Lake Malawi, Lake Tanganyika, and Lake Victoria. Each lake has developed it's own unique habitat and inhabitants.

Along the rift, the northern most lake is Lake Victoria, and Lake Malawi is the southern most lake, with Lake Tanganyika situated between them.

Lake Malawi is the ninth largest lake in the world.with an overall area of about 12,000 square miles. It is the southern most lake of the rift lakes. This lake is bordered by Tanzania, Mozambique, and Malawi. The lake is long, narrow and quite deep, reaching depths of 2,300 feet at its deepest point. Only the upper 300 feet or so contains enough oxygen to sustain life of cichlids. Due to the geography of rapids to the north and south of the lake, this lake is effectively cut off. As a result, the dominant fish family, Cichlidae, have evolved from the riverine forms of Tilapia and Haplochromis have been totally isolated within the lake and have evolved to a point where the lake contains more known cichlid species  than in any other lake in the world. More of the popular species of cichlids among aquarium hobbyists come from Lake Malawi.

Lake Tanganyika contains by far the most unique and diverse array of freshwater fishes of any other lake on earth. NOtably, the cichlids of Lake Tanganyika show the greatest adaptation and uniqueness of shape and habitat preferences than elsewhere in Africa. In a 1986 review, Professor Max Poll defined 12 distinct  lineages among the lake Tanganyika cichlids, as compared to the three groups of Lake Malawi cichlids. Lake Tanganyika is 420 miles long and about 40 miles at its widest point. It's shores are bordered by four countries - Zambia (on the south), Congo (to the west), Tanzania (to the east), and Burundi (on the northeast end). The lake is nearly 4800 feet at its deepest. The pH ranges from 8.7 to 9.4, and the water is quite hard.

Lake Victoria, with its adjoining sister Lake Kyoga, are the northern most of the major African Rift Lakes, and is bordered by three countries - Tanzania to the south, Uganda to the north, and Kenya on the northeastern edge. Lake Victoria is around 240 moles long and about 190 miles wide, with a maximum depth of 300 feet, making it a shallow saucer-shaped lake with a large surface area. This makes it a well oxygenated body of water. The pH ranges from 7.0 to 9.0, and the temperature runs between 70 and 81 degrees F.

The chemical composition of the African Rift Lakes is hard and alkaline.The pH of the water varies from 7.7 to 8.7, and is quite alkaline, and also very hard. In general the water temperature at the shorelines where the cichlids are found averages about 78 degress F.

There is alot of interesting information about why these lakes are so unique. For more detailed about the geography and history of these unique lakes, check out: THE GREAT LAKES OF EAST AFRICA

Tuesday, May 11, 2010

The Aquarium Nitrogen Cycle

The Nitrogen Cycle typically takes approximately 4 to 5 weeks to get to the healthier "nitrate" producing state. This is why you shouldn't add additional fish until the Nitrogen Cycle matures to this point. The good news is that once your tank is properly "cycled" the beneficial bacteria in the aquarium will continuously break down fish waste and uneaten food, helping to keep your tank healthy, as long as you continue routine maintenance.

To illustrate the maturation process of the Nitrogen Cycle in the aquarium, this chart demonstrates what happens to the ammonia (NH3), nitrite (NO2-) and nitrate (NO3-) levels in a new aquarium:  


Here are the basics of how the biological ecosystem in an aquarium matures the Nitrogen Cycle.  Basically, the Nitrogen Cycle is the process where the biological ecosystem disposes of the most toxic Nitrogen based compounds by rendering the poisonous Nitrogen to a less toxic chemical form… 
  • Wastes and debris (like uneaten food) decays and is broken down into AMMONIA (NH3) which is toxic to your aquarium's inhabitants; 
  • Ammonia builds up (see the green bell curve on the chart) while the first significant part of your biological ecosystem, NITROSOMONAS bacteria, grows until it is breaking down the ammonia faster than it is produced. The Nitrosomonas bacteria is specialized to absorb the ammonia, and convert it into NITRITE (NO2-). Nitrites are also toxic to the aquarium's inhabitants; 
  • As Nitrites build up (see the purple bell curve on the chart), the second significant bacteria in your biological ecosystem, NITROBACTER, is triggered to multiply. The Nitrobacter bacteria is specialized to absorb the nitrites, and convert it into NITRATES (NO3-). Nitrates are the least toxic nitrogen-based compound to your aquarium’s inhabitants.

Friday, May 7, 2010

What are MBUNA?

MBUNA - pronounced "Mm-Boo-na"
Mbuna is a native Malawi term (from the local Chitonga language) that means "rock fish". It is not a specific type of fish, but rather refers to the collective group of species that live in the rocky shorelines of Lake Malawi.

Mbuna are not large cichlids. This makes them attractive as inhabitants for the home aquarium. When referring to "Mbuna", numerous African Lake Cichlid species are represented, including species from the popular Genera of  Pseudotropheus (represented by the Zebras), Labeotropheus (represented by the Roman-Nose species), Melanochromis (represented by the Gold Auratus and Chipokae species), Labidochromis (represented by the Yellow Labs), Cynotilapia (represented by the Lion Afra), Gephyrochromis , Iodotropheus (the Rusty Zebras), as well as the Genyochromis, Petrotilapia and Cyathochromis genera. Aulonocara (represented by the Peacocks) are a member of the haplochromines, but are oftern given an honorary status as mbuna.

Blue Cobalt Zebra - Pseudotropheus species

Roman-Nose Mbuna - Labeotropheus species

Gold Auratus (female) - Melanochromis auratus

Rusty Mbuna - Iodotropheus species