To the east of Satara, the S41 gravel road crosses several streams as it winds its way over the plains. Three of these – the Mavumbye, Gudzani and Nwanetsi – usually have water, but owing to good summer rains were flowing especially strongly when we visited during December 2021. While flowing water is always a pleasing sight (and sound), crossing these streams during this latest visit was particularly enjoyable for us as it allowed a glimpse into a facet of the Lowveld ecosystem that is pretty difficult to experience while driving around in a vehicle. With the water flowing over the causeways we were able to watch large schools of juvenile Mozambique Tilapia, as well as the occasional adult, swimming around in the pools on either side of the drifts.
Naturally the Mozambique Tilapia occurs in rivers flowing into the Indian Ocean from the Zambezi River southwards to the Boesmans River and its tributaries in the Eastern Cape of South Africa. They have however been introduced to waters outside this range, both in South Africa and elsewhere in the world, as they are a highly regarded aquaculture species. Regrettably their adaptive nature means that they often outcompete indigenous fish species for food and prime breeding locations in places where they were introduced. Ironically the IUCN considers the Mozambique Tilapia to be vulnerable in its native range due to the introduced Nile Tilapia, with which it hybridizes.
Male Mozambique Tilapia are considerably larger than the females. They grow to about 40cm in length and can weigh over 3kg, though around 1kg is more usual.
Mozambique Tilapia are very adapatable and hardy, being able to live in fresh, brackish and sea water, allowing them to exploit estuaries under the influence of the ocean tides, with water temperatures in the range from below 15ºC to 42ºC. They prefer standing or slow-flowing water. These fish have a varied diet ranging from algae and other water plants to invertebrates and even small fish.
Mozambique Tilapia breed in summer, when adult males sport a deep black body colour with a white throat. The male prepares a saucer-shaped nest on a sandy bottom in which he courts the female. After spawning, the female broods the eggs and fry in her mouth until they are more capable of looking after themselves. In this way she can produce a brood every 3-4 weeks. Young Mozambique Tilapia mature rapidly and can breed within a year of hatching. They may live for up to 11 years.
The following photographs of Mozambique Tilapia were not take during the above-mentioned trip to the Kruger National Park: