Otopharynx lithobates "Zimbawe Rock" male (main) and female (inset)
Name: Otopharynx lithobates
Origin: Lake Malawi
Otopharynx lithobates is a carnivorous Haplochromine from lake Malawi.
O. lithobates is one of the most stunning freshwater fish from lake Malawi, but it does not begin that way. As a juvenile, O. lithobates is a dull brown, laterally compressed fish with little to no colouration. Unless you know what you are looking for, it would be very easy to pass up in your LFS. Once the metamorphosis begins, the face will become a dark blue, and the dorsal fin will range from yellow to orange, depending on the variety. By the end of the first year, the three dark spots on the flank will be all but masked by the spreading blue colouration, eventually covering the entire body. In between year one and two, dominant males will reach full colouration, while the females will retain a juvenile appearance. O. lithobates is a very slow growing species, maturing at a slower rate than comparable species.
Otopharnyx lithobates is a micro predator and does not suffer from the same dietary restrictions as many peacocks and mbuna. I keep O. lithobates in a mixed Malawi tank with peacocks and mbuna, feeding New Life Spectrum exclusively, with excellent results. Otopharynx lithobates also provides a fairly high level of population control. Any fry foolish enough the leave the safety of the rock work is quickly snapped up. Although they are predators, any fish over 3 or 4 cm are safe. They display little to no aggression towards their tank mates, and are only aggressive amongst themselves during breeding.
In my experience, females will hold between 10 and 50 fry. Mouth brooding and care of young is typical to comparable species.
Water quality is very important. A large canister filter is recommended, along with a good power filter and plenty of biological media. Multiple filters and 50% weekly water changes will go a long way in maintaining this species.
Otoparynx lithobates enjoys a pH of 7.8 to 8.6, somewhere in between being ideal. Stability is key. An easy way to maintain a stable pH is to add sodium bicarbonate initially and with each water change if needed. For example, my local water comes out of the tap at a pH of 7.0, KH is 20 ppm and GH of 10 ppm. I use a ratio of 2 tablespoons each of sodium bicarbonate and magnesium sulfate (Epsom salts, to raise GH) to each 100 litres of new water added. This maintains my pH at 8.2, KH at 200 ppm and GH at 120 ppm; well within optimal ranges. Keep in mind that stable water parameters are more important than fluctuations, and unless you know what you are doing, playing with water chemistry could do more harm than good. Warm, 27°C to 28°C, clean, stable water will go along way in maintaining healthy fish.
O. lithobates is best kept in a species only tank, in a ratio of 1 male to 3 females. If kept with other haps or peacocks, no females should be kept of any species. This will help to keep aggression down, and prevent hybridization.
If you are keeping a mixed Malawi tank, haps/peacocks and mbuna, you must choose mbuna carefully. O. lithobates is not aggressive towards mbuna, but can be easily bullied by the more aggressive species. Most pseudotropheus, zebra complex, labeotropheus, etc, should be avoided. P. acei and L. caeruleus make good tank mates, and I have had luck with P. elongatus "chewere". Mixing haps with mbuna is different in every scenario, and if you plan on doing this, you should have a separate tank ready to remove aggressive fish from your mix.
If you decide to keep this species, I suggest raising them from juveniles. Watching the transformation from dull brown juvenile to the vibrant adult it becomes is very rewarding.
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