Fish Lab & Aquaria – Life in the Maldives

Large Marine Aquarium

During July, several of the new corals bleached and died. This included the orange Tubastraea (maybe due to competition, or insufficient feeding) although interestingly the black Tubastraea appears healthy and is feeding well. We also observed some predation by the Moon Wrasse on smaller species, and so we have adjusted the food mix.

Plankton Production

Algae supply remains on a consistent and successful cycle. Artemia production is keeping up with the demand of the main tank, at 6g of cysts a day. Rotifer population has recovered and remains stable, despite the high demand from the large numbers of fish and shrimp larvae in our Fish Lab.

Zooplankton Survey Study

As part of our Zooplankton Survey, our new water quality testing and monitoring kits have arrived, and we have been creating a weekly water quality datasheet of our House Reef lagoon.

🦇 The MDC Goes Batty! 🦇

Our two baby fruit bats have been with us since the middle of June. Both are thriving and are getting bigger and stronger every day. We held a naming competition through Instagram and think they both really suit their new names, Kika and Moosa.

Both bats are now climbing around their home-made ‘jungle gym’ during the day, and spending their nights under cover to protect them from getting wet and cold. Moosa in particular has become very cheeky and has started to climb high into the nearby trees. Although neither has taken their first flight yet, both are working daily to strengthen their wings and are getting much stronger.

Ornamental Fish Breeding

• Clark’s clownfish (Amphiprion clarkii) – The breeding pair in tank #3 are producing eggs again, however, the resulting clutches are weak and are being eaten by their parents before they can hatch. Only a small number have successfully hatched, and those that did died shortly afterwards. The food supply will be increased, with more focus on fish paste and nutrient-loading to increase egg quality.
• Maldivian clownfish (Amphiprion nigripes) – The breeding pair in the main tank continues to perform well, with a total of two spawning events this month. To facilitate egg-collection, we have now relocated the parents and their anemone to Tank #21 for easier access.
• Banded pipefish (Corythoichthys haematopterus) – During July, we collected two male pipefish with brooding eggs in their ventral pouches. We identified their gestational development and managed to successfully collect larvae from both males.
  Pipefish (and seahorses) produce larvae that are fully formed miniature adults, which will not go through a metamorphosis. They are born fully independent plankton-feeders:
  – newborn seahorse mouth gape is only 210µm, so we have started their feed on rotifers;
  – at Day-7 (once the mouth gape becomes 500µm) we will transition to larger 12-hour Artemia.
  Unfortunately, around Day-5 there was a large die-off, despite good rates of feeding observed (but microscope imaging showed possible over-aeration of the swim bladder).
  This group of pipefish is monogamous, so it is unlikely that we will be able to pair these new males with our resident Fish Lab female. Even so, we will watch for regular greeting behaviours, as without daily greetings between mated pairs, there is the potential for recoupling (as observed in the wild).

• Sexy shrimp (Thor amboinensis) – The clutch produced by breeding female A at the start of May continue to do well; the juveniles have now grown into the ‘adult’ stage at Day-74, showing full colouration and the ‘wiggling’ that characterises this species. The seven largest shrimps have been transferred to display Tank #35 with a mushroom coral, for full grow-out before being united with the colony for pairing and future breeding.
  The clutch from female C has survived very well, with a total of 71 larvae (25%) reaching the final developmental stages 7-8. As a trial, a small amount of mushroom coral mucus is being introduced to these shrimps, in an attempt to speed up the settlement process.
  Our new Kreisel tanks (pictured, 2 x 17L, 1 x 25L) will increase our capacity for research into spawning, survival and development of this species.
• Boxer shrimp (Stenopus hispidus) – The breeding pair have bonded well, with no aggression seen even during the reproductive period; their regular cycle consists of spawning/fertilisation (mid-month) followed by hatching 13 days later.
  Three of the larvae collected in June have survived to the final “juvenile” development stage.
  The pair reproduced again, with a total of 550 larvae hatching on 26 July, which were placed in our new 25L circular ephyra Kreisel to increase available space and reduce risks of predation at the later stages.

Jellyfish – Aurelia aurita

Jellyfish numbers remain good, and there is minimal shrinking in the specimens in our main Kreisel display tank (pictured).