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Spawning strategies in cichlids part 5 – Mouthbrooding

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Last updated on 23-Jul-2022

Juan Miguel Artigas Azas,

Classification: Behavior.

" For those fish species that provide care to their eggs or fry, cichlidae is one of the 87 families (21% of the 422 families of teleost) where this is known to happen; in the case of cichlids this is true for all species. In order to better protect their brood, many species have developed the elaborate post-spawning behavior known as mouth-brooding, where either —or both— eggs and fry are held inside the mouth of one —or both— of the parents during a certain amount of time for protection and sometimes feeding of the fry "

Female with fry A female of Nimbochromis polystigma with fry at Gome Rock, Lake Malawi [Malawi]. Photo by Juan Miguel Artigas Azas. (08-Nov-2008). determiner Ad Konings

For those fish species that provide care to their eggs or fry, cichlidae is one of the 87 families (21% of the 422 families of teleost) where this is known to happen (Goodwin et al., 1998); in the case of cichlids this is true for all species. In order to better protect their brood, many species have developed the elaborate post-spawning behavior known as mouthbrooding, where either — or both — eggs and fry are held inside the mouth of one — or both — of the parents during a certain amount of time for protection and sometimes feeding of the fry. This advanced behavior is the most common form of post-spawning care in cichlids. Mouth-brooding has independently arisen multiple times from substrate brooding ancestral species within different lineages of cichlids, both in Africa and in South America (Goodwin et al., 1998). Mouth-brooding has proven to be very successful, such that all species of cichlids in lakes Malawi (over 800 species) and Victoria (over 100 species) use it. In Lake Tanganyika alone, it is estimated that mouth-brooding has independently evolved in five cichlid lineages, each one having developed its own version (Kuwamura, 1997). Mouth-brooding is the rule in Africa, where 94% of genera are known to use this breeding behavior (Barlow, 2001).

Mouth-brooding has likely originated from transportation (in the mouth) of wrigglers between excavated pits during nursing in substrate-brooding species, in particular when the young were retained in the mouth for some time to avoid predation (Lowe-McConnell, 1959). After mouth-brooding was established in species, mouth-brooding by the female alone developed into the most widely used form of breeding in cichlids, evolving independently 21-30 times, versus just one for male mouth-brooding (Goodwin et al., 1998), as I will discuss further in the text.

Advantages of mouth-brooding

Besides the obvious better protection of the eggs and/or fry that mouth-brooding behavior provides, additional benefits are derived from mouth-brooding. Mouth-brooding species are able to be polygynandrous, which means females can get their eggs fertilized by more than one male, increasing the genetic diversity of their fry and arguably the probability of their survival.

Additionally, mouth-brooding offers high mobility, which reflects in parents’ ability to move to better fry-raising areas once they have the fertilized eggs in their mouths. For substrate-spawning cichlids this is most often not possible, since the eggs are firmly attached by threads to a hard surface and they may suffer damage when taking them off (Barlow, 2001). Wrigglers can be moved but just for short distances. In mouth-brooding cichlids, eggs or fry can be moved substantial distances from the spawning site to a more suitable area, for example to an area with better protection from predators, or with more oxygen or food for the fry. In many Lake Malawi cichlid species mouth-brooding females congregate by the thousands in what are known as “nursing areas” (Konings, 2016) where they can brood their fry in the protective environment provided by the large group and/or by the special location.

Females mouth-brooding at Mvgunti Mylochromis plagiotaenia females mouth-brooding at Mvgunti, Lake Malawi [Malawi]. Photo by Ad Konings. determiner Ad Konings

For species where the female does all of the mouth-brooding, the obvious advantage is that the male is free to reproduce again sooner than if he had to participate in brood care, and hence he can produce more fry in a faster way (Goodwin et al., 1998).

Types of mouth-brooding:

Mouth-brooding behavior is not always the same as several different variations have been recorded for cichlids, often with one type of behavior evolving from another but also with different mouth-brooding behaviors evolving independently from each other.

George Barlow (2001) has named and organized the different mouth-brooding techniques, as follows:

In terms of the initiation of the mouth-brooding protection, he classifies them into promptocavus (cavus = cavity + prompte = readily, quickly from Latin) or postponocavus (postpono = postpone from Latin). Promptocavus species immediately pick up the eggs during spawning or with a small delay after the eggs have been deposited by the female, sometimes after fertilization or in some occasions with fertilization taking place inside the female’s mouth. Promptocavus species are also known as immediate or ovophile mouth-brooders.

Examples of promptocavus species are all mbuna species from Lake Malawi and all Haplochromis (and related genera) from Lake Victoria and its smaller surrounding lakes. Males court and lead females to their spawning place and once eggs are released by the female they are immediately taken into her mouth after being fertilized by the male. In some promptocavus Ophthalmotilapia species in Lake Tanganyika females may even get their eggs fertilized once they are inside their mouths.

Postponocavus cichlids are also known as delayed or larvophile mouth-brooders: they pick up the eggs, wrigglers or fry days after spawning has completed. When it concerns the eggs, they are usually taken into the mouth just prior to hatching.

In South America, Satanoperca leucosticta is an example of a postponocavus cichlid: pairs spawn on a flat surface and then often cover the eggs with a thin layer of sand. When hatching approaches, both parents pull the eggs loose and take the newly-hatched wrigglers into their mouths (Leibel, 1992). Most mouth-brooding South American cichlid species are postponocavus. In Africa, one example of a postponocavus species is Benitochromis batesii, the breeding behavior in captivity of which is detailed by Link & Staeck (1994:31). Pairs spawn in caves and the eggs are deposited on the ceiling of the cave, where they are closely guarded by the female while the male defends the territory. Once the eggs hatch, the female takes the wrigglers into her mouth where they stay until they become free swimming, at this point they are released and the male joins in the care of the fry until they become independent.

Adult in the aquarium Satanoperca leucosticta is an example of a postponocavus cichlid. Photo by Juan Miguel Artigas Azas. determiner Radek Bednarczuk

In terms of mouthbrooding cooperation there are three different behaviors detailed by Barlow (2001): duocavus, patricavus, and matricavus; the meaning of each should be obvious. By far, the most common behavior is matricavus, more commonly referred to as maternal mouth-brooders. All cichlid species in Lake Malawi (827) are matricavus (Konings, 2016) as well as those in Lake Victoria (Seehausen, 1996) and likely all Haplochromines. Even in Lake Tanganyika, where a much higher diversity of breeding behaviors have evolved, only about 13% of the species are duocavus whereas in around 44% of the cichlid species the female is the exclusive parent (Konings, 2019).

Duocavus species are small in number in the cichlid family, with only 21% of the mouth-brooding cichlid genera containing species using it (Goodwin et al., 1998), but in South America most mouth-brooder species are duocavus, like for example Satanoperca leucosticta, Heros liberifer, Apistogramma barlowi, and others.

In Africa, many Oreochromini are duocavus. The widely distributed Sarotherodon galilaeus for example is a monogamous species with a prolonged courtship. Once the female spawns and the non-adhesive eggs are fertilized, both male and female pick up part of the eggs and depart in separate ways (Barlow, 2001:71). Other examples of duocavus cichlids in Africa are several species of Benitochromis in West Africa, and in Lake Tanganyika species in the genera Eretmodus, Gnathochromis, Greenwoodochromis, Haplotaxodon, Limnochromis, Perissodus, Reganochromis, Tanganicodus, to name a few.

Adult in the aquarium Sarotherodon galilaeus is an example of a duocavus species where male and female pick-up part of the eggs. Photo by Anton Lamboj. (28-Mar-2005). determiner Anton Lamboj

Patricavus, or paternal mouth-brooders are so far only known from Africa and they are rare, at least in cichlids, since it is a dominant mouth-brooding behavior in other fish families. Only two cichlid genera contain patricavus species as far as we known: Sarotherodon and Chromidotilapia. One of the patricavus species according to Lamboj (2004) is Chromidotilapia guentheri, a species with a wide distribution in West Africa. C. guentheri are monogamous cichlids which produce adhesive eggs (not common for mouth-brooders). Just after deposition and fertilization of the eggs, the male C. guentheri takes the entire clutch into his mouth, where it remains for the entire incubation time. The female performs the role usually performed by the male in other species, i.e. defending the territory. Once the fry are free swimming they are released by the male and both partners defend them until the end of brood care, about a month after spawning. Another patricavus species is Sarotherodon melanotheron, and it is likely that other Sarotherodon species are as well (Trewavas, 1983).

In terms of length of care for the fry there are two behaviors: iterocavus (itero = repeat from Latin) and semelcavus (semel = once, one time from Latin). Iterocavus species keep guarding their fry once they are released from the mouth by the parent(s) that brood them, often allowing them back into the mouth cavity, while semelcavus cichlids don’t provide any further care once the fry are released.

All known mouth-brooding South American cichlids are iterocavus, providing prolonged care for their progeny once they are released. In Lake Tanganyika, species of Haplotaxodon and Perissodus are examples of iterocavus mouth-brooding behavior.

Iterocavus behavior was initially thought to be the typical mouth-brooding behavior for cichlids, but now we know that many species are semelcavus. Typically semelcavus species are also matricavus, or maternal mouth-brooders, with few exceptions. Most mbuna and utaka cichlids in Lake Malawi are semelcavus, meaning that once the fry are released no further care is given by the parent, in this example the female. Semelcavus cichlids typically produce fewer but larger eggs than iterocavus species, since the fry must be able to survive without further assistance once released.

Barlow further details the duocavus behavior establishing categories for what he describes as cedocavus, which are biparental mouth-brooders where at one point a partner cedes the care of eggs, wrigglers, or fry to the other partner, either partially or complete. For example, in Benitochromis species in West Africa females partially cede the mouth-brooding care of the fry to males (Lamboj, 2004).

One interesting behavior is for a parent to cede the fry to other parents; which is known as “farming out” (Barlow, 2001). The most amazing case is known as “interspecific farming out”, where the recipients of the ceded fry are pairs of a different species. Farming out is common in substrate brooders but not so in mouth-brooders. Ochi & Yanagisawa (1996) studied several Lamprologines from Lake Tanganyika where half of the pairs contained fry from other cichlid species, accounting for 20-40% of the total young. A receiving (host) mouth-brooding species was found in Perissodus microlepis. The ceding (guest) cichlid species were varied and included the mouth-brooders Haplotaxodon microlepis and even Cyprichromis species! It was found that some of the host species also perform as guest species.

Adult in the aquarium Sarotherodon galilaeus is an example of a duocavus species where male and female pick-up part of the eggs. Photo by Anton Lamboj. (28-Mar-2005). determiner Anton Lamboj

Parasitism

Not all is positive with mouth-brooding. Several species have been able to evolve sneaky behaviors to take advantage of mouth-brooding. One well known example is performed by the cuckoo catfish Synodontis multipunctatus in Lake Tanganyika, which is able to mix its fertilized eggs in with that of the mouth-brooding cichlid batch during the brief period where the female, after laying the eggs, wants to pick them up into her mouth. The catfish eggs then develop faster than the eggs of the host and once they hatch munch on the nutritious eggs of the host, all inside the mouthbrooder’s mouth. Interestingly, cichlid species are learning and have engaged in an evolutionary arms race with the catfish by rejecting its eggs even at the cost of rejecting also their own, as was observed in Ctenochromis horei and Simochromis diagramma from Lake Tanganyika (Blažek et al., 2018).

In Lake Victoria several species have found a way to extract eggs, larvae, and fry out of the mouth of mouth-brooding females. Examples are the Haplochromis species previously known from the genus Lipochromis. In Lake Malawi some Caprichromis species even ram mouth-brooding females from below on the throat forcing the release of eggs or fry, which are then quickly ingested.

Conclusion

Beyond what I have exposed in this short article where I have just scratched the surface of mouth-brooding in cichlids, there are many fascinating evolutionary and behavioral adaptations that mouth-brooding has produced and that have been studied, and I am certain that many more are still to be discovered. Next time you see a cichlid mouth-brooding, think of the complex evolution that has produced that sophisticated breeding technique.

I want to thank Ad Konings for his critical review of this article and his valuable comments.

References (14):

Citation:

Artigas Azas, Juan Miguel. (July 23, 2022). "Spawning strategies in cichlids part 5 – Mouthbrooding". Cichlid Room Companion. Retrieved on August 09, 2022, from: https://cichlidae.com/section.php?id=327.