That Fish Blog – Aquarium Advice and Information

September was a bad month for Honolulu Harbor and all of the fantastic fish, corals and wildlife that called it home. On September 09, 2013 over 233,000 gallons of molasses spilled into the harbor, sinking to the sea floor and suffocating everything in it’s wake. The cracked pipe that allowed the mess to flow into the harbor was repaired within days, but the damage caused by the viscous mess has been rapid and devastating.

You think of molasses and you don’t think of widespread death, but flood a pristine marine environment with sugary syrup and that’s the result. The heavy fluid ends up being lethal in several ways.  The goop clogs gills, suffocating fish quickly. It coats corals and inverts, robbing them of light, oxygen and water flow vital to their ability to thrive. The sugars are also a rich food source for marine bacteria which reproduce in massive numbers, depleting dissolved oxygen as their numbers grow.  The dissolved sugar alters the pH of the water and also creates what’s called an osmotic effect, basically dehydrating marine organisms whose living cells expel water in an attempt to equalize with their external environment. Within hours the death toll began to rise, and to date thousands upon thousands of fish, inverts, corals and even other animals like sea turtles have perished. 

Unlike oil spills that may be wicked off of the surface of the water, the nature of this spill means that cleanup of the molasses itself is not an option. The syrup will dissolve and nature will slowly eat it up and wash it out of the harbor and into the sea. Clean-up in this case means fix the leak, monitor the progress of the damage, and collect the carnage of dead sea creatures that wash up on shores and pile up in shallow areas so that predators like sharks and barracuda aren’t attracted to area. While some creatures may bounce back and return to the harbor pretty quickly, it may be years until the coral reefs, vital to the economy and ecology, in the harbor recover.

What a sad situation. Unfortunately, the only real course of action is to allow nature to clean up another man made mess. On the bright side, nature knows how to take care of herself, and despite the scope of the problem, this particular spill is in many ways still better than oil or some other chemical deluge. Now all anyone can really do is wait and see…

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 »

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.  October, 2012’s Hurricane Sandy wrecked havoc on fish keepers and public aquariums in the Northeastern USA.  My own collection, which houses several 20-30 year-old catfishes, loaches and aquatic amphibians, suffered only a single loss.  I owe a debt of gratitude to the dedicated folks at That Fish Place-That Pet Place, who shipped much-needed supplies to me in record time, despite the disastrous weather.  The public aquariums for which I consult are now working frantically to limit losses; I’ll provide updates via Twitter.

Most aquarists know what steps to take during power outages, so today I’d like to focus on several points that, in my experience, are sometimes over-looked.

Filter Care and Bacteria Die-offs

When power fails, submersible, corner, and other internal filters should be removed from the aquarium.  When oxygenated water is flowing through a filter, waste material is processed by beneficial aerobic bacteria, and ammonia is converted to less toxic nitrites and nitrates (please see this article).  Once the flow of water stops, the resident beneficial bacteria perish.  Without aerobic bacteria, your filter becomes a source of decomposing organic material, quickly poisoning the already-stressed aquarium inhabitants.

As the contents of external aquarium filters are not in direct contact with the water, they will not immediately add to the pollution problem.  However, these filters should be disconnected because when electric power is restored, they will pump ammonia and other toxins into the tank. Read More »