1

Zebra Mbuna (Maylandia zebra) Ecological Risk Screening Summary

U.S. Fish and Wildlife Service, February 2011 Revised, July 2018

Web Version, 8/3/2018

Photo: Bardrock. Licensed under CC BY-SA 4.0. Available:

https://commons.wikimedia.org/wiki/File:Maylandia_zebra_-_ZOO_Edynburgh.JPG. (July

2018).

1 Native Range and Status in the United States Native Range From Froese and Pauly (2018):

“Africa: Endemic to Lake Malawi [Malawi, Mozambique, Tanzania]. Occurs on the

northwestern coast between Cape Manulo and Kande Islands. Also found on Jalo Reef, at

Namalenje Islands, Cape Maclear, Monkey Bay, Boadzulu Islands and Nkopola. On the eastern

part, occurs at Fort Maguire, Masinje on Likoma and Chisumulu Islands [Konings 1990].”

2

Status in the United States From Nico (2018):

“Status: Reported from Nevada.”

“The first report of this fish in Nevada was by a member of the American Cichlid Association,

who observed several specimens of the "marmalade" form of P. zebra during a visit to Rogers

Spring, a tributary of Lake Mead near Overton, Clark County, in July 1981 (Courtenay and

Deacon 1982). Later records from Rogers Spring included a single male fish taken on 14

November 1981 (Courtenay, personal communication), and several individuals reportedly found

in 1983 (Courtenay, personal communication). These records were apparently the basis for the

listing of the species in later publications as introduced but not established in Nevada (e.g.,

Deacon and Williams 1984; Courtenay et al. 1984, 1986, 1991; Courtenay and Stauffer 1990;

Vinyard 2001).”

The most recent observation of M. zebra in Nevada occurred in 2001 (Nico 2018).

This species is in trade in the United States.

From Imperial Tropicals (2015):

“Metriaclima Zebra Dwarf Manda (F-1) […] $ 7.99”

Means of Introductions in the United States From Nico (2018):

“Probable aquarium release.”

Remarks Maylandia zebra was originally described as Tilapia zebra and has also been known as

Pseudotropheus zebra and Metriaclima zebra. All names were used in searching for information

to inform this report.

There is conflicting information on the correct taxonomy for this species.

From Eschmeyer et al. (2018):

“Current status: Valid as Maylandia zebra (Boulenger 1899). Cichlidae: Pseudocrenilabrinae.”

From Kasembe (2017):

“This species previously appeared on the IUCN Red List in the genus Maylandia but is now

considered valid in the genus Metriaclima (Konings 2016, Stauffer et al. 2016).”

3

From Nico (2018):

“According to Eccles and Trewavas (1989), the genus Pseudotropheus is in particular need of

revision and critical appraisal. Pseudotropheus zebra alone represents a complex of about 27

species (Ribbink et al. 1983).”

2 Biology and Ecology Taxonomic Hierarchy and Taxonomic Standing From ITIS (2018):

“Kingdom Animalia

Subkingdom Bilateria

Infrakingdom Deuterostomia

Phylum Chordata

Subphylum Vertebrata

Infraphylum Gnathostomata

Superclass Actinopterygii

Class Teleostei

Superorder Acanthopterygii

Order Perciformes

Suborder Labroidei

Family Cichlidae

Genus Metriaclima

Species Metriaclima zebra (Boulenger, 1899)”

From Eschmeyer et al. (2018):

“Current status: Valid as Maylandia zebra (Boulenger 1899). Cichlidae: Pseudocrenilabrinae.”

Size, Weight, and Age Range From Froese and Pauly (2018):

“Max length : 11.3 cm SL male/unsexed; [Maréchal 1991]”

Environment From Froese and Pauly (2018):

“Freshwater; demersal; pH range: 8.0 - 8.0; dH range: 9 - 19; depth range 6 - 28 m. […] 22°C -

28°C [Riehl and Baensch 1991; assumed to be recommended aquarium temperature range];”

Climate/Range From Froese and Pauly (2018):

“Tropical; […] 8°S - 15°S”

4

Distribution Outside the United States Native From Froese and Pauly (2018):

“Africa: Endemic to Lake Malawi [Malawi, Mozambique, Tanzania]. Occurs on the

northwestern coast between Cape Manulo and Kande Islands. Also found on Jalo Reef, at

Namalenje Islands, Cape Maclear, Monkey Bay, Boadzulu Islands and Nkopola. On the eastern

part, occurs at Fort Maguire, Masinje on Likoma and Chisumulu Islands [Konings 1990].”

Introduced

This species has not been reported as introduced or established outside of its native range and the

United States.

Means of Introduction Outside the United States This species has not been reported as introduced or established outside of its native range and the

United States.

Short Description From Froese and Pauly (2018):

“Dorsal spines (total): 16 - 19; Dorsal soft rays (total): 7-10; Anal spines: 3-4; Anal soft rays: 6 -

9. Diagnosis: head moderately sloped; rostral tip of the neurocranium swollen; jaws isognathus;

outer rows of the jaws with bicuspid teeth; absence of any interrupted pigment in the pale blue

dorsal fin in combination with black bars on a blue ground; gill rakers on first ceratobranchial 8-

14; gill rakers on first epibranchial 1-3 [Stauffer et al. 1997]. Females with gray/blue to

blue/brown ground color and no yellow pigment in unpaired fins, ocelli in anal fin present

[Konings and Stauffer 2006].”

From Stauffer et al. (1997):

“Breeding males have a blue ground coloration laterally with 6-8 black vertical bars, very faint

or no bars on posterior one-third. Although extremely rare, a few males in some populations (e.g.

Songwe Hill) exhibit a blue/black or orange/black blotched coloration. Belly anterior to the

pelvic fins (P2) black fading to light blue posteriorly; head dark blue to black with a single light

interorbital bar; gular dark gray in most populations, but yellow in some northern populations.

Dorsal fin uniformly blue gray in most populations, with tips of posterior rays orange in some

populations and a continuous black horizontal stripe in some northern populations; caudal fin

blue/gray; anal fin blue gray with 1-5 yellow ocelli; in some populations the proximal two-thirds

of the anal fin is black, while the distal one-third is light gray; P2 light blue leading edge, spine

and first two rays black, posterior rays clear; P1 clear. Females generally with brown cast and 1-4

faint ocelli on anal fin. The females alternatively may be dull blue or exhibit an orange/black

blotched coloration. This blotched coloration is observed more frequently in females than males

and appears to be completely absent in some populations.”

5

Biology From Kasembe (2017):

“Occurs in rocky habitats (can be either sediment free or sediment rich). Feeds at right angles

with the substrate combing loose material from the rock surface. It is often observed feeding on

plankton from the open water. Male territories consist of caves which they defend and where

spawning occurs. Females are found in groups foraging in the water column. It is a polymorphic

cichlid.”

From Froese and Pauly (2018):

“Produces up to 60 eggs.”

From Streelman et al. (2007):

“Individual zebra can feed in two different ways (McKaye & Marsh, 1983). The elongated,

terminal mouth is well adapted to suck plankton from the water column. In addition, individuals

brush algae and detritus from sediment covered rock surfaces with an outer row of comb-like

bicuspid teeth (Reinthal, 1990). The diet of M. zebra varies geographically and seasonally

(Eccles, 1974; Haberyan & Mhone, 1991; Bootsma & Hecky, 1993).”

Human Uses From Froese and Pauly (2018):

“Aquarium: highly commercial”

From Nico (2018):

“This species or species complex is well known in the aquarium trade.”

Diseases From Froese and Pauly (2018):

“White spot Disease, Parasitic infestations (protozoa, worms, etc.)

Fin Rot (early stage), Bacterial diseases

Trypanosoma Infection, Parasitic infestations (protozoa, worms, etc.)

Hole-in-the-Head Disease, Parasitic infestations (protozoa, worms, etc.)

Pseudomonas infection, Bacterial diseases

Bacterial Infections (general), Bacterial diseases

Cryptobia Infestation, Parasitic infestations (protozoa, worms, etc.)”

Poelen et al. (2014) reports Acanthogyrus tilapiae as a parasite of Maylandia zebra (Strona et al.

2013).

No OIE-reportable diseases have been documented for this species.

6

Threat to Humans From Froese and Pauly (2018):

“Harmless”

3 Impacts of Introductions From Nico (2018):

“Unknown.”

4 Global Distribution

Figure 1. Known global distribution of Maylandia zebra in Lake Malawi, eastern Africa. Map

from GBIF Secretariat (2018).

7

5 Distribution Within the United States

Figure 2. Known distribution of Maylandia zebra in the Lake Mead area of Nevada and Arizona

in the United States. Map from Nico (2018). Eastern occurrence point represents a centroid, not a

precise occurrence location. The other occurrence point represents a record of a population of M.

zebra that was reportedly established in Rogers Spring in 1984. According to Nico (2018), the

last observation of M. zebra in Nevada occurred in 2001. Because the establishment status of this

population is uncertain, it was excluded from climate match analysis.

8

6 Climate Matching Summary of Climate Matching Analysis The Climate 6 score (Sanders et al. 2014; 16 climate variables; Euclidean distance) for the

contiguous United States was 0.000, which is a low climate match. The range for a low climate

match is from 0.0 to 0.005, inclusive. The climate score was low in every state in the contiguous

United States. Southwest Florida, far south Texas, southern Arizona, and the southern California

coast had areas of medium climate match.

Figure 3. RAMP (Sanders et al. 2014) source map of southeastern Africa showing weather

stations selected as source locations (red; Malawi, Mozambique, Tanzania) and non-source

locations (gray) for Maylandia zebra climate matching. Source locations from GBIF Secretariat

(2018). Selected source locations are within 100 km of one or more species occurrences, and do

not necessarily represent the locations of occurrences themselves.

9

Figure 4. Map of RAMP (Sanders et al. 2014) climate matches for Maylandia zebra in the

contiguous United States based on source locations reported by GBIF Secretariat (2018). 0=

Lowest match, 10=Highest match.

The “High”, “Medium”, and “Low” climate match categories are based on the following table:

Climate 6: Proportion of

(Sum of Climate Scores 6-10) / (Sum of total Climate Scores)

Climate Match

Category

0.000≤X≤0.005 Low

0.005<X<0.103 Medium

≥0.103 High

7 Certainty of Assessment There is adequate information available about the biology, ecology, and distribution of

Maylandia zebra. This species has been documented as introduced outside of its native range,

but the current status of the population is unknown, and no information is available on impacts of

this introduction. Further, there is some uncertainty about the taxonomy of this species, including

what genus in belongs in and whether it is one species or a complex of species. Because further

information is needed, certainty of this assessment is low.

10

8 Risk Assessment Summary of Risk to the Contiguous United States Maylandia zebra, the Zebra Mbuna, is a cichlid species endemic to Lake Malawi in eastern

Africa. It is used in the aquarium trade, including in the United States. M. zebra can be afflicted

by numerous bacterial diseases and parasitic infestations. This species has a low climate match

with the contiguous United States, although there are a few small areas of medium climate match

in the southeast and southwest. M. zebra was reported from Rogers Spring, Nevada in 1981 and

1983; however, no M. zebra have been observed in Nevada since 2001 and no information is

available on the current status of this population. No impacts of introductions of this species have

been documented in the scientific literature. The introduction is believed to be from an aquarium

release. There is some uncertainty about the taxonomy of this M. zebra, including what genus it

belongs in and whether it is one species or a complex of species. Because of a lack of

information from which to base an assessment of risk, the certainty of this assessment is low.

The overall risk assessment category is uncertain.

Assessment Elements History of Invasiveness (Sec. 3): None Documented

Climate Match (Sec. 6): Low

Certainty of Assessment (Sec. 7): Low

Overall Risk Assessment Category: Uncertain

9 References Note: The following references were accessed for this ERSS. References cited within quoted

text but not accessed are included below in Section 10.

Eschmeyer, W. N., R. Fricke, and R. van der Laan, editors. 2018. Catalog of fishes: genera,

species, references. Available:

http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp.

(July 2018).

Froese, R., and D. Pauly, editors. 2018. Maylandia zebra (Boulenger, 1899). FishBase.

Available: https://www.fishbase.de/summary/Maylandia-zebra.html. (July 2018).

GBIF Secretariat. 2018. GBIF backbone taxonomy: Maylandia zebra (Boulenger, 1899). Global

Biodiversity Information Facility, Copenhagen. Available:

https://www.gbif.org/species/2373039. (July 2018).

Imperial Tropicals. 2015. Metriaclima Zebra Dwarf Manda (F-1). Available:

https://imperialtropicals.com/collections/african-cichlids/products/metriaclima-zebra-

dwarf-manda-f-1. (July 2018).

11

ITIS (Integrated Taxonomic Information System). 2018. Metriaclima zebra (Boulenger, 1899).

Integrated Taxonomic Information System, Reston, Virginia. Available:

https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=648

227#null. (July 2018).

Kasembe, J. 2017. Metriaclima zebra (amended version of 2006 assessment). The IUCN Red

List of Threatened Species 2017: e.T61155A120778246. Available:

http://www.iucnredlist.org/details/61155/0. (July 2018).

Nico, L. 2018. Pseudotropheus zebra (Boulenger, 1899). U.S. Geological Survey,

Nonindigenous Aquatic Species Database, Gainesville, Florida. Available:

https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=474. (July 2018).

Poelen, J. H., J. D. Simons, and C. J. Mungall. 2014. Global Biotic Interactions: an open

infrastructure to share and analyze species-interaction datasets. Ecological Informatics

24:148-159.

Sanders, S., C. Castiglione, and M. H. Hoff. 2014. Risk Assessment Mapping Program: RAMP.

U.S. Fish and Wildlife Service.

Stauffer, J. R., Jr., N. J. Bowers, K. A. Kellogg, and K. R. McKaye. 1997. A revision of the blue-

black Pseudotropheus zebra (Teleostei: Cichlidae) complex from Lake Malawi, Africa,

with a description of a new genus and ten new species. Proceedings of the Academy of

Natural Sciences of Philadelphia 148:189-230.

Streelman, J. T., R. C. Albertson, and T. D. Kocher. 2007. Variation in body size and trophic

morphology within and among genetically differentiated populations of the cichlid fish,

Metriaclima zebra, from Lake Malawi. Freshwater Biology 52(3):525-538.

10 References Quoted But Not Accessed Note: The following references are cited within quoted text within this ERSS, but were not

accessed for its preparation. They are included here to provide the reader with more

information.

Bootsma, H. A., and R. E. Hecky. 1993. Conservation of the African great lakes: a limnological

perspective. Conservation Biology 7:644–656.

Eccles, D. H. 1974. An outline of the physical limnology of Lake Malawi. Limnology and

Oceanography 19:730-742.

Haberyan, K. A., and O. K. Mhone. 1991. Algal communities near Cape Maclear, southern Lake

Malawi, Africa. Hydrobiologia 215:175-188.

Konings, A. 1990. Konings's book of cichlids and all the other fishes of Lake Malawi. TFH

Publications, New Jersey.

12

Konings, A. F., and J. R. Stauffer, Jr. 2006. Revised diagnosis of Metriaclima (Teleostei:

Cichlidae) with description of a new species from Lake Malawi National Park, Africa.

Ichthyological Exploration of Freshwaters 17(3):233-246.

Maréchal, C. 1991. Pseudotropheus. Pages 401-415 in J. Daget, J.-P. Gosse, G. G. Teugels, and

D. F. E. Thys van den Audenaerde, editors. Check-list of the freshwater fishes of Africa

(CLOFFA). Volume 4. ISNB, Brussels, Belgium; MRAC, Tervuren, Belgium;

ORSTOM, Paris.

McKaye, K. R., and A. C. Marsh. 1983. Food switching by two specialized algae-scraping

cichlid fishes form Lake Malawi, Africa. Oecologia 56:245-248.

Reinthal, P. N. 1990. The feeding habits of herbivorous rock-dwelling cichlid fishes (Cichlidae:

Perciformes) from Lake Malawi, Africa. Environmental Biology of Fishes 27:215-233.

Riehl, R., and H. A. Baensch. 1991. Aquarien atlas volume 1. Mergus, Verlag für Natur-und

Heimtierkunde, Melle, Germany.

Strona, G., M. Lourdes, D. Palomares, N. Bailly, P. Galli, and K. D. Lafferty. 2013. Host range,

host ecology, and distribution of more than 11800 fish parasite species. Ecology 94:544.