Home / Fishes / Cichlids / Cichlidae / William's mbuna

No federal permit to keep

William's mbuna

Maylandia greshakei

Also known as Greshakei

Fishes › Cichlids (Cichliformes) › Cichlidae (Cichlids)

William's mbuna (Maylandia greshakei), also known as ice blue zebra mbuna or ice blue zebra or the Pseudotropheus ice blue among the aquarium enthusiasts, is a species of cichlid fish endemic to Lake Malawi where it is only found at Makokola in the…

Aquarium hobby

Experience: Easy

William's mbuna — Photo: (c) Klaus Rudloff, some rights reserved (CC BY-SA), CC BY-SA 4.0, via iNaturalist

Photo: (c) Klaus Rudloff, some rights reserved (CC BY-SA), CC BY-SA 4.0, via iNaturalist

FamilyCichlids

Adult lengthup to 5.3 in

WaterFreshwater

Care at a glance

Species-specific aquarium care

Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 5.3 in / 13.4 cm).
Water: Freshwater.
Temperature: 75–79°F (range recorded for this species).
Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
Diet: A plankton picker: offer small, frequent feedings of fine frozen and live foods (copepods, brine shrimp, daphnia). FishBase classes it as a herbivore.

Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.

Care guide

Species care notes

Tank: a base of at least 35 × 18 in (roughly 41 US gallons); space needed is rated “large tank”.
Water: hard, alkaline water, 75–82 °F, pH 7.6–8.8, 10–25 dGH.
Behaviour: temperament territorial.
Difficulty: Moderate (Seriously Fish rating).

Short excerpts from the species profile:

Setup: “Much of the aquarium should contain piles of rocks, arranged to form caves with small areas of open water between.”
Diet: “It will accept most foods offered but vegetable matter in the form of spirulina flakes, blanched spinach etc.”
Tankmates: “Aggressive and territorial.”

From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167

Group care guide

Lake Malawi mbuna

Applies to most species in this group. Habitat: Rocky shores of Lake Malawi. Individual species can differ, so compare with the species numbers above and the linked sources.

Housing & setup

Hard, alkaline water (pH 7.8–8.6) and lots of stacked rock with caves; a long tank (often 4 ft+).
Keep in crowded groups of one male to several females per species, to spread aggression.

Sources 117 119 164 118 255

Climate & lighting

Water

76–82°F

Sources 117 119 164 118 255

Diet

Choose diet by mbuna species. The L. caeruleus profile offers vegetable foods alongside live or frozen foods; do not impose a universal ban on animal protein.
Feed small amounts once or twice a day.

Sources 117 119 164 118 255

Social life

Territorial; overstock mbuna-only tanks rather than mixing with peaceful fish.

Sources 117 119 164 118 255

Health watch

Monitor water quality, feeding and aggression. Do not present dietary protein alone as a confirmed diagnosis or universal cause of abdominal swelling.

Sources 117 119 164 118 255

Understanding the animal

About this animal

This species can reach a length of 13.4 centimetres (5.3 in) TL. It can also be found in the aquarium trade. The specific name honours the German ornamental fish importer Alfons Greshake.

Quoted from the Wikipedia article “William's mbuna” (CC BY-SA 4.0) 174

In the wild

From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.¹

Where it lives	Lives in freshwater. Stays near the bottom. Inhabits the rocky biotope of the reefs, where the rocks are permanently covered with a layer of sediment. Feeds mainly from the phytoplankton in the open water. Territorial males feed from the biocover on the rocks.
Water it lives in	Freshwater, 75–79 °F (24–26 °C), depth 15–35 m.
Climate	Tropical climate.
Wild diet	Selective plankton feeding.
Behavior to plan for	Breeding: external brooders.

What this means for care

Keep water within its wild range, 75–79 °F.

FishBase species summary: Maylandia greshakei

From the sources

Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.

Overview	William's mbuna (Maylandia greshakei), also known as ice blue zebra mbuna or ice blue zebra or the Pseudotropheus ice blue among the aquarium enthusiasts, is a species of cichlid fish endemic to Lake Malawi where it is only found at Makokola in the southeastern arm of the lake. This species can reach a length of 13.4 cm TL. It can also be found in the aquarium trade. The specific name honours the German ornamental fish importer Alfons Greshake. — Wikipedia (community-edited)
Where it lives	Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase
Biology	Inhabits the rocky biotope of the reefs, where the rocks are permanently covered with a layer of sediment. Feeds mainly from the phytoplankton in the open water. Territorial males feed from the biocover on the rocks. — FishBase

Data and studies

The numbers

Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.

Adult length

Average of sources5.3in

FishBase 1645.3

Seriously Fish species profiles 1675.3

Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.

Water temperature

Average of sources75–80.5°F

FishBase 16475–79

Seriously Fish species profiles 16775–82

Range the species tolerates in nature; aim for the middle.

pH

Reported7.6–8.8

Seriously Fish species profiles 1677.6–8.8

Water hardness

Reported10–25dGH

Seriously Fish species profiles 16710–25

Minimum tank footprint

Reported35in

Seriously Fish species profiles 16735

Seriously Fish recommends a tank base of at least 35 × 18 in (about 41 US gallons).

Federal legal snapshot

No federal permit to keep

No federal law singles out this species for private keepers. State and local rules still apply.

State law decides most of it. Each state sets its own permits and bans for exotic, native, venomous and dangerous animals, and cities and counties can be stricter. Find your state agency →

Not covered by the Animal Welfare Act

The Act only covers warm-blooded animals. Reptiles, amphibians, fish and invertebrates have no federal care standards, even at licensed facilities; state and local rules may still apply.

Kept in captivity?

Every species on this site needs evidence that people actually keep it. For this one:

Has a Seriously Fish aquarium species profile
FishBase records it in the aquarium trade (Aquarium=commercial; AquariumFishII=based mainly on breeding)
13 iNaturalist observations of captive animals

Sources for this sheet

FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
Merck Veterinary Manual: Types and features of aquatic systems Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
Merck Veterinary Manual: Nutritional diseases of fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
Seriously Fish — Labidochromis caeruleus Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.