That Fish Blog – Aquarium Advice and Information

Gorgonians, also known as Sea Fans or Sea Whips, are beautiful and fascinating creatures found throughout the world’s oceans. These creatures are rather iconic, their branched or net-like structures adding a different dimension to a reef, swaying gently with the current.  Gorgonians are flexible, stationary cnidarians though they are very similar to soft corals. Individual tiny polyps form colonies in a variety of sizes and shapes. Some are stiff and erect, resembling the veins of a leaf, some resemble ribbons with polyps aligned on the edges, others look like plumes or are branched like trees. There are also single strand colonies and those that encrust on rock in thin sheets. They are often brightly coloured, purple, red, orange or yellow, and polyps may be white, brown, yellow or some other pale shade.

About Gorgonians

More than 500 described species of Gorgonian are found tropical and subtropical oceans around the world. More species are found in the tropical Atlantic that in other regions. They usually grow in shallow waters, though there are some species that grow in depths of more than 1000 ft. Shallow water species tend to be more flexible and broad to withstand currents while deeper water types grow tall, thin, and more rigid. They may grow anchored to solid surfaces like rock or coral, or they may “root” in loose gravel or sediment.  Gorgonian colonies are supported by an internal, ridid central skeleton covered with softer tissue that connects each polyp to the next to form the colony. The structure a gorgonian colony creates varies between species from a simple whip-like form to complex net-like fans that can be several feet tall and wide.

Gorgonians provide a secure home to many other maring species including brittle stars, bryozoans and hydrozoans. Pygmy seahorses (Hippocampus bargibanti) cling to several specific species and have adapted to blend perfectly with the colonies with color and texture specic camouflage.  You may also find tiny species of crabs, shrimp, gobies, blennies, and other creatures have also adapted to thrive amongst the polyps and branches of Sea Fans.

Choosing a Gorgonian

It’s important to recognize a healthy gorgonian when you’re ready to put one in your tank. Carefully examine your choices, looking for any signs of damage to the skin. Have the person helping you look gently turn each specimen in the water, so you can get a full look, and take notice of any damage, missing tissue, or flaking or peeling of tissue when the specimen is moving. Smell the water in the holding tank. If there is a noticeable odor, avoid the tank, as it may be sign that one or more of the gorgonians is rotting. Look for one with a thick, sturdy, uncut stem or base, and at least a few extended polyps.

Gorgonian Care

Care of gorgonians will vary greatly according to the species you acquire, and you should take care to research the variety before purchase to ensure that you can provide what it needs to thrive.  That being said, most of the common species available in the trade have relatively simple needs.

When you place your new gorgonian in the tank, give it plenty of space where it can sway with the current, completely submerged and without touching other corals or surfaces. Be sure to orient your Sea Fan in good, strong, direct current to ensure they are exposed to plenty of food when it is added to the tank. The water flow will also provide the tissue with plenty of oxygen and keep the surface free of waste and debris. The specimen should be mounted upright and with plenty of light exposure.

Gorgonians are filter feeders. Each tiny polyp has eight tentacles used to catch phytoplankton and other tiny particles carried to them in the current. Many prefer to feed at night, so generally this is when you’ll see the polyps emerge. There are many commercial invertebrate food options available to offer gorgonians. You may also offer them tiny frozen foods like rotifers, cyclopeeze and baby brine shrimp. Administer a small amount of food to entice the polyps to open, then follow a short while later with a larger dose when the most of the polyps are extended.

Many Gorgonians are also photosynthetic, containing symbiotic algae in their polyps that provide a secondary energy source for the colony. Fro these species it is vital that strong light is provided. Photosynthetis species typically have brown or green polyps as opposed to those lacking pigmentation.  These species may grow rapidly when kept in ideal conditions, and periodic pruning may be required. See this article for detailed info on pruning and propogation.

Be aware before you purchase a gorgonian that many fish and inverts may see them as a new meal. Keep a watchful eye for crabs, snails, slugs and other predators that can quickly damage your fan. Gorgonians also play host to lots of other organisms, so don’t panic right away if you find tiny serpent stars, anemones or other creatures from your tank amongst the branches.

Gorgonian image referenced from wikipedia and originally posted by Nobgood
goby on Gorgonian image referenced from wikipedia and originally posted by Jenny (jennyhuang) from taipei

Fishes are the most numerous and diverse of all vertebrates, so it’s no surprise that many fascinating new species were discovered in 2012.  Among them were 9 brilliantly-colored American Darters and a Vietnamese fish that carries its sexual organs on its head (dubbed, for the lack of a better name, the Genitalia-Headed Fish).  Shallow Tennessee streams, ocean trenches nearly 2 miles deep, Indonesian coral reefs and many other habitats yielded wonderful surprises, and hinted that fish enthusiasts have much more to look forward to. Today I’ll highlight a few grabbed my attention; please post your own favorites (whether covered here or not) below.

US Darters: the Obama Fish and other “Politicos”

Nine new species of freshwater Darter were described from the southeastern USA this past year (Bulletin of the Alabama Museum of Natural History).  Five were named in honor of the environmental awareness exhibited by current and former politicians: Etheostoma obama, E. teddyroosevelt, E. gore, E. jimmycarter and E. Clinton. Read More »

The choices for lighting your aquarium have never been so vast. Whether you are setting up a new aquarium, replacing an old light fixture, or adding to your existing light, there are many decisions to be made.  New technology, and improvements on older lighting methods, provide today’s aquarium hobbyist with a dizzying array of lighting choices for any aquarium. So, how do you choose? What is the best light for your aquarium?

Here are a few questions to ask yourself, to help you with the decision:

Is the light that you are looking for only going to be used on your current aquarium habitat, or are you planning on a more advanced aquarium in the future that may require a higher output light source? You may want to consider a stronger light than you need for your current livestock, as basic lighting may limit what you can keep in the tank down the line.   Read More »

Hello, Frank Indiviglio here. In 2001, I wrote a book about the Natural History and Care of Seahorses. As I intended, many readers were discouraged, due to the demands involved in their care and the fragile state of wild populations. Today, I am happy to report that captive-born individuals of several species are regularly available, and that the task of feeding them (a major stumbling block) has been greatly simplified.  Still, they are not ideal for every aquarist. Following are some important points to consider before you decide to keep these intriguing but challenging fishes. 

Seahorses Need a Wide Variety of Small, Live Foods

The world’s 130+ seahorse species (Family Syngnathidae) are strict live food specialists. Brine shrimp, the most easily-obtained seahorse food, is suitable as a steady diet for only one, the Dwarf Seahorse, Hippocampus zosterae (please see this article). Most others avidly consume brine shrimp, but will not survive long without amphipods (scuds, side-swimmers), sand hoppers, tiny shrimp, Mysids and similar marine creatures. Read More »

Hello, Frank Indiviglio here.  The world’s 30-35 freshwater sunfish species (Family Centrarchidae) range throughout Canada, the USA and Central America.  Although popular among European aquarists, sunfishes have been largely been neglected in American aquaculture. This is a shame, as all are colorful, interesting and active, and most adjust well to aquarium life. From the tiny Black-Banded Sunfish to the 39 inch long Largemouth Bass, there is something for everyone.  I’ve had the good fortune of working with a “sunnies” ranging from the tiny Black-Banded Sunfish to the massive Largemouth Bass, and would enjoy hearing from readers who have also come to know them, or wish to (please post below).

Obtaining Sunfishes

Although rarely offered in the pet trade, many species are easily collected via seine net or minnow trap (check state regulations).  While their diversity is greatest in the southeastern USA (my friend in Louisiana collected 8 species in the lake behind his house!), sunfishes can be found most everywhere in the USA. New York, where I reside, is home to 14 species. Read More »