Home / Fishes / Silversides and rainbowfish / Delicate blue-eye
No federal permit to keepDelicate blue-eye
Pseudomugil tenellus
Fishes › Silversides and rainbowfish (Atheriniformes) › Pseudomugilidae (Blue-eye rainbowfish)
The delicate blue-eye (Pseudomugil tenellus) is a species of fish in the subfamily Pseudomugilinae.
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 1.6 in / 4 cm; the largest recorded was 2.2 in).
- Water: Freshwater.
- Temperature: 77–95°F (range recorded for this species).
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Availability: Rarely or never seen in the aquarium trade; expect to source it from specialists or not at all.
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 30 × 12 in (roughly 18 US gallons); space needed is rated “modest tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 77–90 °F, pH 5.5–7.5, 5–20 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more; suited to a community tank.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Best kept in a densely-planted tank and an excellent choice for the carefully-aquascaped set-up.”
- Diet: “Feeds chiefly on floating or suspended zooplankton, phytoplankton, algae, and invertebrates in nature, with the principal constituents of the diet changing with the time of year.”
- Tankmates: “Peaceful and suitable for well-chosen community aquaria alongside fishes of comparable size, disposition, and requirements with many cyprinids, gobiids, eleotrids, and smaller melanotaeniids suitable.”
- Breeding: “This species is an egg-scatterer exhibiting no parental care and will consume its own eggs and fry given the opportunity.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Blue-eye rainbowfish
Applies to most species in this group. Habitat: Blue-eyes occupy Australasian streams and vegetated freshwater margins, with some Pacific blue-eye populations also using brackish mangrove creeks. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Spotted blue-eyes: tank base at least 18 × 12 inches; forktail blue-eyes: at least 24 × 12 inches.
- Plant densely, including floating vegetation and roots that shade the upper water.
- Provide a biologically mature aquarium with well-oxygenated water and some flow.
- For breeding provide fine aquatic moss or spawning mops; adults can eat eggs and fry.
Climate & lighting
| Water | 75.2–82.4°F |
Diet
- Live Daphnia or Moina sized to the fish
- Artemia nauplii
- Microworms
- Small or crushed floating dried foods
Social life
- Keep spotted blue-eyes in shoals of at least 8–10 with similarly small, peaceful companions; avoid competitors that monopolize food.
Health watch
- Ammonia toxicity in immature systems
- Hypoxia
- Inbred forktail stocks can produce deformed fry and reduced fertility
Understanding the animal
About this animal
About this animal
It is found in northern Australia and Papua New Guinea.
Quoted from the Wikipedia article “Delicate blue-eye” (CC BY-SA 4.0) 174
In the wild
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 swamps and quiet backwaters of streams with mud or gravel bottoms and abundant vegetation including water lilies. Usually found in waters exposed to full sunlight. |
| Water it lives in | Freshwater, 77–95 °F (25–35 °C). |
| Climate | Tropical climate. |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
What this means for care
- Keep water within its wild range, 77–95 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 96°F (up to 99°F in the hottest sampled areas) |
| Cool-season lows | about 62°F (down to 58°F in the coldest sampled areas) |
| Average temperature | 80–82°F across sampled records |
| Relative humidity | 60–68% on average (driest month about 50%) |
| Rainfall | about 1474 mm a year, with strong wet and dry seasons |
Measured at 30 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
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.
| 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 swamps and quiet backwaters of streams with mud or gravel bottoms and abundant vegetation including water lilies. Usually found in waters exposed to full sunlight (, 44894 ). Occurs in marshy ponds (billabongs), overflow pools of rivers and creeks Occurs at temperatures ranging from 25°-35° C. Possibly more widespread, but has escaped detection due to its small size and inconspicuous appearance. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Common length to maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 30 × 12 in (about 18 US gallons).
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.
- Seriously Fish: Pseudomugil gertrudae Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Pseudomugil furcatus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- FishBase: Pseudomugil signifer Peer-reviewed researchAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Common Environmental Hazards for Fish 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.
