Aquatic Advisory, Greater Kailash, Delhi

15/12/2023

"Bryde's Whale"
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This was one of the most amazing experiences I've ever had in the water. As with many of my favorite captures, it happened on a day we least expected. Yesterday was a long day, but totally worth the journey for this experience.
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Special thanks to for once again hosting me on an incredible journey and for letting me use my drone to help find sealife. While I love aerial photography , my true passion is the camera in my hand while I'm in the water. Let me know if you want to join me on a future adventure.

15/12/2023

We came across a striking pair of Swallowtail Headshield Slugs (Chelidonura hirundinina) on our recent trip to Parker Point, Rottnest Island. The name “Swallowtail” derives from a characteristic split in the tail, similar to the tail of its namesake, with the left side always being longer than the right. Headshield slugs have a broad front of the head (resembling a shield, which stops sand from entering the mantle cavity when burrowing). Many marine slugs the Clade Cephalaspidea are voracious carnivores, feeding on nudibranchs, snails, worms, and other slugs 😊

15/12/2023

15/12/2023

15/12/2023

16/09/2023

Today, I was asked by an aquarist, why his prize fish, a Moorish idol, Zanckus cornutus, was grazing his Zoanthus polyps. Bedevilled as he was, the answer lies in the biologies of these marine organisms.

A moorish idol will, unfortunately, eat cnidarians that don't sting powerfully, or contain noxious defences. So they will not consume stinging, clown fish hosting anemones or Euphyllia corals, for example. This is the feeding ecology of Zanckus, it is a nibbling grazer of sessile organisms, especially sponges, but also corals. Because such foods are ubiquitous on the reef, these fishes graze constantly, without storing extra for future energy in their body mass.

For this reason, they starve during long haul shipping and acclimatisation, and the stress is the cause of their notorious mortality. When Moorish idols are not subject to such stresses, such as long term captives seeking rehoming, or locally caught fish, they are actually extremely hardly.

In the wild, Zoantbus sp. are pretty much limited to predator free environments, such as rock pools, which is why they are so hardy in aquaria. Their evolutionary history is the story of how they survived by avoiding predators, by colonising difficult habitats. Their retreat to low predation environments, also means these animals have no real defences, against opportunistic grazers from other environments.

Unlikely culprits like Zebrasoma tangs and sargeant majors, will develop a taste in the aquarium, for the unprotected meat of Zoanthus. Whereas the related Palythoa should be safe, for obvious reasons related to their palytoxin, a chemical defence.

Zoanthus are hardy and very suitable for beginners, but very prone to becoming the targets, even of unexpected corallivores. On the other hand, moorish idols are difficult to ship, but they are not inherently hard to keep. If you have one that actually is eating naturally, like a wild fish, it will be tough as boots when it can graze organisms from rocks all day. But one must expect a natural, even if non-obligate corallivore, to consume live corals.

23/05/2023

It is true that decapods obtain shell-building materials from the surrounding water, so in theory, raising the hardness makes sense. But a number of shrimp and crayfish species, in the freshwater tropical aquarium trade, are inhabitants of softer water than people assume out in the wild. They can't need the aquarist to dose very much, unless the water parameters are very off

01/05/2023

Today, I was asked if a plate coral (or fungiid coral, to the zoologist) will kill or consume clownfishes. Fortunately, clownfish species in the wild, have been recognised to faculatively choose plate corals as hosts. Very nice corals and very nice fish, but I found that fungiid tent to start turning black and rotting on the underside. Despite the biotope aquarium, being favorable to their health, in principle. Other than the reputation of Heliofungia as extremely difficult, it isn't clear what causes the tissue dieback. And it seems, for now, either the aquarist has luck with these species, or does not. Other than physically resembling anemones, these stony corals have large mouths, and a macrocarnivorous tendency. Feeding them a swallowable-sized chunk of meaty food, maybe once a week, does them well. Good luck.

18/03/2023

Today, I was asked about the suitability of Canthigaster valentini, and it's congeners, for the reef aquarium. Sadly, despite the repetition of misinformation, this fish is a risk to other motile and sessile reef organisms. Its is considered to be truly omnivorous, consuming a variety of benthic organisms - from filamentous algae, to forams, to poriferans, to polychaetes, to small arthropods. The diet of Canthigaster sp. in the wild, definitely includes coral polyps as well, so these miniature pufferfishes, fall short of reef safe

15/03/2023

Someone is importing Selheim's sole (Brachirus selheimi) into Europe, which is interesting. Because this is a true or pleuronectiform flatfish, indigenous to riverine environments in the tropical North of Australia, and its categorised as a freshwater to estuarine fish. In freshwaters, B. selheimi is reportedly found on shallow, sandy bottoms, and in deeper rock pools.

As a soleid or true sole, B. selheimi is, of course, an ambush predator, consuming small fishes and arthropods. Yet, growing itself to only 25 cms or 6 ins, most intended tankmates should escape predation. Obviously, very small fish or shrimp will not be suitable companions. Not counting predatory habits, pleuronectiforms are passive and peaceful aquarium fishes, so other bottom dwellers in the aquarium, should not be too hectic in their movement.

This species is being traded simply as the 'freshwater sole', which is apt to create confusion, because a number of flatfish species, including mislabelled brackish flatfishes, are sold by this label. The correct common name, is Selheim's sole. Confusingly the species, or a lookalike, is being traded also as the 'Papuan sole'. Given that the tropics of northern Australia and adjacent, southern New Guinea, share many species or species complexes, it would not be surprising if New Guinea exports do represent B. selheimi or extremely similar fish.

Allen et al. (2003) regard Selheim's sole as entirely freshwater, so there's no need to add salt. If one does, it should be at a low salinity, as for guppies rather than for scats and monos. Temperture, pH and hardness values, as for rainbowfishes from the same rivers, should do this species just as fine.

27/02/2023

I have been asked about the ease, or difficulty, of keeping cerianthids - the beautiful tube or fireworks 'anemones' - in the marine aquarium. Fortunately they are easy to care for, although because they are lacking photosynthetic symbionts, they will need feeding with small, meaty pieces, perhaps twice a week.

Cerianthids need only a mild water flow, enough to blow away their wastes. Intense light for them is nsturally unneccessary, because they lack photosynthetic symbionts. However they are best not maintained, under very strong daytime lighting, if you wish to see them extend their crowns out of their tubes. I have maintained them under low and medium light regimens, under which they extended fully by day.

These anthozoans, which are not true sea anemones or actinarians, do need a deep, soft substrate of fine sand or mud, with particles of 4mm or less in diameter, into which they will bury themselves, and withdraw if disturbed. Technically they will be withdrawing into a self-made tube structure. For up to the crown of its tentacles, the cerianthid will secrete a tube of syncretic composition, comprising modified nematocysts, threads of its own musus secretions, and particles of the surrounding substrate.

These anthozoans do have the ability to sting, and the length of their expanded outer or marginal tentacles, means they should be positioned far from sessile animals, such as corals. In the confines of too small an aquarium, they might also sting fish that brush against them, for the venomous tentacles are toxic also to motile animals, such as shrimp and fish - and they will not play host to clownfishes.

Cerianthids use their outer tentacles, to sweep the surrounding substrate for benthic prey, though they do take prey from the water column also. Items thus siezed are transferred from the outer to the inner tentacles, to be passed along further, to the oral cavity for ingestion. The largest prey taken by cerianthids, are probably about 2 centimeters long, and the primary prey of these animals are benthic arthropods, much smaller than that. Some ornamental decapods will thus be in particular danger, from sharing their aquarium, with a cerianthid.

Cerianthids are rarely, if ever, identified to species level in the aquarium trade. More likely they will be vaguely identified, perhaps with a reference to their color as a further specifier, for example, a cerianthid that is a striking purple, will likely be traded as a 'purple fireworks anemone'.

24/02/2023

Today I was, asked about an unusual, bottom dwelling fish traded as a 'lizard blenny'. In fact the fish in question, is known properly as a, sandperch, or Parapercis sp. These, are not a staple import of the marine aquarium trade, so it's unsurprising they are misunderstood to be blennies, and mistraded as such. Another trade name for sandperches, are the sandhopper blennies, though they are emphatically not blennies.

Sandperches are fortunately hardy carnivores, harmless to corals and tridacnid clams, but unfortunately prone to eating their fish and shrimp tankmates. This is in marked contrast to the benthic blennies, that are predominantly algivorous or detrivorous.

Sandperch lack a swim bladder, and as such rest on the substrate. In the wild, they inhabit areas of sand or rubble. This demersal nature is the habit that confuses aquarists, into misidentifying them as blennies. You should consider these ambush predators, more as you would a hawkfish.

The matured size of these fishes unfortunately varies by species, yet the species is unlikely to be identified, at the point of retail. One species I have identified in the trade, P. schauinslandii, the red spotted sandperch, grows to 18 centimeters, or a little beyond 7 inches. However other Parapercis from tropical waters, potentially grow to 'nearly a foot' or short of 30 centimeters. A fish this size may be characterful, but a danger to very small tankmates. They can be fed on defrosted, meaty fare of the sort usually intended, for crustacean- and fish-eating fishes.

I'm actually fond of the sandperch clade, and do not wish to disuade other aquarists from keeping the characterful genus. Other than to caution that they are mis-sold as blennies, even though their dietary habits are dissimilar, and some popular reef tank staples will not be safe when there is a big sandperch lurking around.