What size tank does a Gertrude's Blue Eye need?

Gertrude's Blue Eye needs a minimum of 5 gallons, with 8 gallons recommended. They are middle swimmers. Keep in groups of 6+.

Is Gertrude's Blue Eye good for beginners?

Gertrude's Blue Eye is rated "intermediate" difficulty (2/5). Great for beginners.

What fish are compatible with Gertrude's Blue Eye?

Gertrude's Blue Eye is peaceful. Compatible tank mates include other peaceful fish with similar water parameters (pH 5.5-7.5, temp 75-82°F).

Gertrude's Blue Eye

Pseudomugil gertrudae

Family: Pseudomugilidae • Origin: Various

Gertrude's Blue Eye (Pseudomugil gertrudae) is a peaceful rainbow reaching 1.5 inches. Keep in groups of 6+. Minimum tank size: 5 gallons.

Min Tank

5 gal

Max Size

1.5"

Temperature

75-82°F

5.5-7.5

Lifespan

2 years

School Size

Swim Level

middle

Hardness

5-15 dGH

peacefulintermediateomnivoreschooling

Is Gertrude's Blue Eye Right for Your Tank?

Gertrude's Blue Eye is an excellent choice for beginners — rated "intermediate" difficulty (2/5). They're hardy, forgiving of minor water parameter fluctuations, and generally easy to feed. At just 5 gallons minimum, they work well in nano tanks and smaller setups.

With a peaceful temperament, Gertrude's Blue Eye makes a great community fish. They coexist well with other non-aggressive species of similar size. This is a schooling species — keep at least 6 together, or they may become stressed and display abnormal behavior. Expected lifespan: 2 years with proper care.

Common Mistakes with Gertrude's Blue Eye

✗

Keeping fewer than 6 together

Gertrude's Blue Eye is a schooling species — they need a group of at least 6 to feel secure. Lone or paired individuals become stressed, hide constantly, and may develop health issues or aggression.

✗

Relying on a heater without a thermometer

Gertrude's Blue Eye needs 75–82°F. Heaters malfunction or drift over time — always use a separate thermometer to verify. Temperature swings of even 3–4°F can trigger stress and disease, particularly ich.

✗

Putting them in a tank under 5 gallons

While 5 gallons is the minimum, nano tanks require more frequent water changes and leave less room for error. A slightly larger tank (8 gal) is much more forgiving.