That Fish Blog – Aquarium Advice and Information

Hello, Frank Indiviglio here.  I’m partial to snails…from tiny stream dwellers indigenous to the spray zone of one waterfall in NY to the huge lumbering African land snails, all that I’ve worked with have been fascinating.  But aquarists often have a love/hate relationship with snails, searching for one that will consume unwanted algae while not eating plants or over-populating the tank.  Enter the olive nerite, a/k/a black marble or Alexander snail (Vittina usnea, formerly Neritina reclivata alexandre).

Natural History

Amazingly, this adaptable snail, native to brackish water habitats in Florida and throughout the Caribbean and Gulf of Mexico, thrives equally well in fresh, brackish or marine aquariums.  It will, however, only reproduce in brackish or marine waters, and so is an ideal choice for freshwater aquarists who fear snail population explosions. 

In the wild, the olive nerite ventures far up rivers, often being found miles away from the sea.  It seems unlikely that such a small creature would migrate back to the ocean to reproduce, so it may breed at the river’s bottom, where denser marine waters penetrate at high tide.  It is theorized that this unusual mollusk may be in the process of evolving from a marine to a purely freshwater creature.

Olive Nerites in the Aquarium

Another point to recommend the olive nerite is the fact that it feeds only upon the brown and green algae that often coats plant leaves, rocks and aquarium glass, and leaves living plants untouched.  When algae populations decline, its appetite can be easily satisfied with algae wafers  and Spirulina discs.

The attractive shell of marble-sized olive nerite is often colonized by tiny barnacles, adding to its interesting appearance.  They are as resilient to environmental conditions as they are to habitat changes, doing well at temperatures ranging from the upper 40’s to the upper 90’s (F) and in waters of 6.3-8.4 in pH.

Related Snails

Two purely marine relatives of the olive nerite, Neritina  funiculata and Vittina luteofasciata, are sometimes offered for sale as well.  They have wider appetites than their more popular cousin, but do best in marine aquariums that support red and brown algae.

Further Reading

Detailed information and a key to the snails of Florida has been posted by the Florida Museum of Natural History at http://www.flmnh.ufl.edu/malacology/fl-snail/snails1.htm.

Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

Image Neritina reclivata is of a related species, referenced from Wikipedia and originally posted by ictheostega.

Eileen here.

One of the most iconic images of a jellyfish, the one most people think of, is that of a dome-shaped animal with long flowing tentacles drifting through the water. For the aquarium community however, this is not the one that we usually see in our tanks. A far more common aquarium jellyfish is the Upside-down Jellyfish.

There are about five different species of Upside-down Jellyfish, found mostly in the Caribbean and tropical western Atlantic Ocean. One of these species in particular, Cassiopea andromeda, has made its way to the Hawaiian Islands and seems to have established itself as a nuisance in waters around the state. It is another species, Cassiopea frondosa, that is usually found in the aquarium trade.

All jellyfish are planktonic by nature, meaning they move with the flow of the water instead of swimming against it. The Upside-down Jellyfish does not actually live in the water column like most other jellyfish. Instead, they use their bell much like an anemone uses its foot to attach to the bottom of a shallow environment like a lagoon, mangrove swamp or sand flat. While this attachment isn’t nearly as strong as an anemone, it helps the jellyfish to remain relatively stationary with its tentacles pointed up towards the surface.  The bell will often pulsate slightly to create a weak water flow over its tentacles which the jellyfish uses to filter-feed small food particles from the water. Upside-down jellyfish also have stinging cells known as nematocysts on its tentacles which it can use to stun larger prey. This feeding helps supplement its diet, but most of the jellyfish’s nutrition comes from the symbiotic algae in its tissue. The sunlight filtering through the water feeds the algae, which in turn produces food for the jellyfish while the jellyfish provides protection for the algae by keeping it alive in its tissue.

Upside-down Jellyfish are one of the easiest types of jellyfish to keep in home aquariums but still require special care and attention. As these animals can reach a diameter of almost a foot across, they should have plenty of flat, open sandy area to spread out. They also need very bright light to feed the algae in its tissue as well as periodic target feeding with foods like brine shrimp, baby brine shrimp, cyclops, zooplankton, phytoplankton and dissolved organic foods. The flow in the tank should be moderately low and any filter intakes should have some sort of covering to make sure the jellyfish doesn’t get sucked up by the current. The stinging cells on their tentacles can also harm other tankmates; do not keep with any shrimp, gobies or other invertebrate or small fish that can become food! These nematocysts can also sting aquarists so take care not to come into contact with the tentacles.

The flower-like appearance, unusual behavior and relatively easy care are making this jellyfish gain in popularity among home aquarists. With some extra TLC and research, Upside-down Jellyfish can truly be a unique addition to a home aquarium!

Patty here. Often brackish fish are a hard sell to people on the market to start an aquarium.  Fish appropriate for brackish systems don’t tend to be as colorful or as easy to mix in communities as many other types of fish, or so many think.  But though these fish are often banished to a remote corner of the fish shop, and often seem too complicated to keep, there is one fish in particular that may be the one to convince you to try your hand at a brackish system.

Archerfish are a common offering in the trade, but their brackish classification and simple beauty may keep them hidden from the view mainstream aquarium enthusiasts.  They are native to India, Southeast Asia, Australia and other countries of the western Pacific.  They prowl through estuaries and mangroves mostly, but may be found upstream in full freshwater or on reefs periodically.

The Banded Archerfish (Toxotes joculatrix), the species commonly offered in the trade, is modestly colored with a tan-grey dorsal area and a pale silvery-white body.  Bold black markings camouflage them from prey and predator above.  They have a compressed body with a flat area from the dorsal fin to the mouth which allows them to move along just under the surface of the water. The mouth is angled upwards.

The most fascinating thing about Archers is their unique and famed ability to shoot their prey.  These fish are skilled predators that are able to snipe insects from branches and foliage 3-5 feet above the surface.  The fish shoots several droplets of water, quickly correcting any error in trajectory and aim to knock prey from the safety of the canopy to the water’s surface where the fish devours its meal.  They may also leap from the water to catch prey that is within reach or dine on small shrimp and fish in the water, but in the wild they commonly swim in groups of “shooting parties”, working together to pick off unsuspecting bugs. With the right set up, you can witness this behavior in your own living room!

This species can reach a max size of up to 12 inches in the wild, so habitat size is the first thing to consider.  They can be expected to reach about 8-10 inches in captivity, and the minimum size aquarium is 55 gallons.  Larger, deeper tanks are better!  Though juveniles may tolerate freshwater environments for some time, as the fish mature a brackish level of 1-2 percent will be necessary (roughly 8-15 teaspoons of aquarium salt per 10 gallons).  The ideal set-up is one that allows for plenty of room to swim and terrestrial areas or areas of open air (like a large tank filled half or 3 quarters full/paludarium set-up) to make the fish happy and allow for a great show! 

You can furnish the tank with salt tolerant vegitation both in terrestrial areas and submerged, driftwood, root wood, rock, and sand or fine gravel.  Good filtration is a must! Though the fish are hardy, they like clean water like that where they are found in the wild.  Once in their new home these fish will quickly resume normal hunting activities, and a batch of live crickets will make for some sport.  These fish will also eat frozen and freeze-dried foods.  Other fish can also be housed with archers as long as they are tolerant of brackish conditions, large enough not to be considered prey, and not overly boisterous.

Hello, Frank Indiviglio here.  Until recently, freshwater shrimp have largely been ignored in the US aquarium trade. I’ve kept a few native species over the years, and was awed by some huge, long-clawed specimens that I collected and released in Costa Rica.  But it wasn’t until I visited Japan several years ago that I became aware of the scores of small, colorful Asian and South American shrimps that were being bred and sold regularly there.  Happily, most of those I came across at that time are now well established in the trade here in the USA.

Environment and Tankmates

The following shrimps will co-exist with one another, provided the dietary needs of the specialists are met.  All thrive at temperatures of 74-80 F and a pH range of 6.5-7.5.  They do best in heavily planted aquariums with moderate water flow and, like many invertebrates, are very sensitive to ammonia.  Many species appear somewhat social, congregating together, and most gravitate to and forage on driftwood if such is provided. 

Freshwater shrimps may be housed with small, peaceful aquarium fishes, but will be attacked buy predatory species and crayfishes.  I have had very good luck in keeping breeding groups with guppies, armored cats (Corydoras spp.) and hill stream, coolie and yo-yo loaches.

Feeding Shrimp

All the following species consume algae, with some favoring hair algae, but they also take a wide variety of flakes, pellets, carrion and organic detritus.  Shrimp of all types are seemingly always foraging, day and night, and should be provided with a wide variety of food options. 

In addition to live algae, I offer freshwater shrimps tropical fish flakes, shrimp pellets, spirulina tablets and live brine shrimp.  If water quality is not an issue, it is also a good idea to allow them to feed upon an occasional small, dead fish.

Amano or Japanese Marsh Shrimp and Relatives, Caridina multidentata

This East Asian import was one of the first species established here, and is still a favorite.  Please see the article referenced below for further information.

The closely related dwarf blackberry shrimp and emerald green shrimp, both native to Thailand, are beautifully patterned and may hybridize with the amano shrimp.  All three prefer to feed upon hair algae, but will take a wide variety of other foods.

Bumblebee Shrimp, Caridina trifasciata

Another Japanese import, the bumblebee is strikingly marked in black and white and possessed of a squat build that makes it seem larger than its ¾ inches.  Voracious scavengers as well as algae eaters, a group of these beautiful shrimps makes a spectacular display.

Orange Halo or Bee Shrimp, Caridina sp.

Favoring hair algae, this native of Thailand is bright orange in color and reaches ¾ inches in length.  In common with its relatives, the orange bee shrimp does best in groups.

Pearl or Snowflake Shrimp, Macrobrachium mirabile

A giant among the dwarf shrimp, this long-clawed species may top 2 inches in length.  It hails from India, where it favors the brackish water of river mouths.  Captives do fine in freshwater, however, and make excellent scavengers.  Despite its size, it is inoffensive to its smaller cousins.

Further Reading

For information on keeping the popular amano, cherry and bamboo shrimps, please see An Introduction to Freshwater Shrimps.

To learn more about a truly unique shrimp, please check out my article Keeping the African Giant Filter Shrimp.

Next time I’ll cover a few species that are rather new to the trade, as well as some more colorful and unique favorites.  Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

Hello, Frank Indiviglio here.  With rigid bodies propelled “helicopter fashion” by tiny fins, the 33 marine species that comprise the Family Ostraciidae are quite amusing as they motor about.  Their appeal is heightened by an “alert” face and, in many, horn-like projections at the head and rear.  Some species grow quite large and require unique diets, but several make interesting, appealing aquarium subjects.

A hard bony carapace protects cowfish relatives from attack by many predators.  However, all are slow moving, and their rapidly undulating fins seem to draw attacks from smaller fish.  Oddly enough, the skin over their rigid protective plates is quite sensitive.  Be sure to watch your specimens closely, lest wounds inflicted by tiny fishes go un-noticed and lead to infection or stress-related diseases.

A 40+ Year Old Memory of a Long Horn Cowfish, Lactoria cornuta

A brilliant yellow body highlighted with blue spots and set off by “horns” at the head and rear renders this droll fish instantly recognizable.  I have a soft spot for these comical fellows.  Back in the early 1960’s, when my grandfather lured me into keeping marine fishes, a long horn cowfish was my first exotic species.  Armed with pioneering marine aquarist Robert Straughan’s 1959 classic The Salt Water Aquarium in the Home, we frequented the 2 NYC aquarium stores (1 in the Bronx, 1 in lower Manhattan) that stocked marine fishes.  Shipments were irregular at the time, but we lucked out on 1 trip with a gorgeous cowfish. 

All-glass tanks were not yet available, so we installed our prize in a large plastic aquarium, where he impressed me greatly by being the only one of  my early purchases to survive my clumsy attempts at marine fish husbandry! 

Slow feeding and peaceful (although aggressive towards other cowfishes), the long horn is one of the few fishes that I was able to house with another long-time favorite, the Atlantic seahorse. 

Hovercraft Boxfish, Tetrosomus gibbosus

This species’ mode of swimming truly fits its name, with only the fins fluttering, propeller-like, as the rigid body moves along.  They are extremely inquisitive, seeming to notice and examine all happenings within and outside of their aquarium.

Maturing at a mere 4 inches in length, hovercrafts are an excellent choice for those lacking space to house long horn cowfishes and other large species.  They are, however, slow to feed, and so their condition should be monitored closely…the stomach areas of underfed boxfishes will rapidly take on a sunken appearance.  However, when housed with other small, methodical feeders (seahorses and pipefishes are worth a try), hovercrafts do quite well.

Husbandry Considerations

Many cowfish relatives are, despite their “apparent calmness”, quite excitable.  Frightened specimens will release a skin-generated poison into the water.  Known as ostracitoxin, this secretion is toxic to other fishes, and, in close quarters, to the toxin-producer itself. 

Establishing cowfishes in an aquarium before adding other species, and choosing only slow-moving, peaceful tank-mates, will go a long way in preventing disasters.  In a dark room, always turn a small room light on before using the aquarium canopy light.

In the wild, cow, box and trunkfishes feed largely upon algae and sessile invertebrates (i.e. sponges, tube worms).  Captives take a wide variety of frozen, freeze-dried  and algae-based foods, along with live brine shrimp, mysids and blackworms.

Further Reading

For further information on the long horn cowfish, please see Species Profile: the Long Horn Cowfish.

Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

Image referenced from Wikipedia and originally posted by LASZLO ILYES