Description

The Blue Assessor Basslet (Assessor macneilli) is a striking and popular saltwater fish known for its vibrant, deep blue coloration and unique behaviour, including swimming upside down. Here’s a care guide for your location in Caboolture, Queensland, Australia:

Care Level: Moderate. They are generally hardy once acclimated but require specific tank conditions and can be sensitive to poor water quality.

Size: They typically reach a maximum size of around 3 inches (7.6 cm) in the aquarium.

Tank Size:

• A minimum tank size of 30 gallons (approximately 114 liters) is recommended for a single Blue Assessor.
• Larger tanks are necessary if you plan to keep multiple individuals.

Water Parameters:

• Temperature: 72-80F (22-27C) – Consistent temperatures are important, so you may need a heater during cooler months in Queensland. Monitor closely during hot summer months to prevent overheating.
• Salinity: 1.020-1.026 specific gravity. Use a refractometer for accurate readings.
• pH: 7.8-8.5
• Alkalinity: 6-12 dKH
• Nitrate: Below 20 ppm
• Phosphate: Below 0.1 ppm
• Maintain stable water parameters through regular testing and water changes using high-quality saltwater mix and RODI (reverse osmosis deionized) water, as tap water in Queensland can be harmful to marine life.

Temperament and Tank Mates:

• Semi-aggressive and Territorial: Blue Assessors can be territorial, especially towards their own kind or similar-looking basslets. It’s generally best to keep only one per tank unless the aquarium is very large (55+ gallons) with ample hiding places, and all individuals are introduced simultaneously.
• Compatible Tank Mates: They generally do well with peaceful to semi-aggressive fish that won’t bully them. Good choices include:
  • Clownfish
  • Wrasses
  • Blennies
  • Gobies
  • Cardinals
  • Pipefish
• Avoid:
  • Aggressive fish that may harass them.
  • Other basslets unless in a very large, well-established tank with plenty of space and hiding spots.

Diet:

• Carnivorous: Blue Assessors require a diet rich in meaty foods.
• Offer a variety of:
  • Mysis shrimp (highly recommended)
  • Brine shrimp (vitamin-enriched)
  • Finely chopped fresh or frozen marine fish and squid
  • High-quality carnivore pellets and frozen preparations
• Feed 2-3 times daily in small amounts.

Aquarium Setup:

• Ample Live Rock: Essential for providing hiding places, caves, and overhangs, which mimic their natural habitat and reduce stress. They are often seen swimming upside down under ledges.
• Substrate: A sandy substrate is ideal but not strictly required.
• Good Filtration: A protein skimmer is highly recommended to maintain excellent water quality.
• Moderate Water Flow: They are not strong swimmers, so avoid very strong currents.
• Tight-Fitting Lid: Blue Assessors are known to jump, especially when startled. A secure lid is crucial.

Important Considerations for Caboolture, Queensland:

• Temperature Stability: Be vigilant about maintaining stable water temperatures throughout the year, considering both cooler winter nights and hot summer days.
• Water Quality: Using RODI water for mixing saltwater and top-offs is crucial to avoid introducing harmful elements from tap water.

By providing the appropriate environment and diet, you can enjoy the unique beauty and behaviour of the Blue Assessor Basslet in your saltwater aquarium. Remember to quarantine any new arrivals before introducing them to your main tank.