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Contains articles featuring information, advice or answering questions regarding aquarium fish and other livestock.

Refugiums for Marine Aquariums

CaulerpaYou may have heard the term refugium if you’re in the aquarium hobby, but do you know what it is and the benefits it can bring to your set-up? A refugium is  essentially a safe area for inverts and macro algae, but it also acts as a biological filter to help control nitrates and phosphates. Refugiums may be part of your sump, a separate hang on back unit, or even another tank plumbed into the display tank system. Generally, it consists of a deep sand bed (DSB), live rock, and macro algae with very slow water flow through the area and a relatively strong light source to support the live plants and inverts you choose to put inside. The light should be in the spectrum between 5,500-8,000k to allow for proper photosynthesis.

Refugium Styles

Let’s take a look at the different styles of refugiums first. One of the most common types is the in-sump refugium. This is a chamber in the sump that has a slow flow (roughly 30% of the water flow from your overflow box) moving through it. This flow rate allows the macro algae and beneficial bacteria to remove waste and nutrients. The best in sump refugium designs are set-up so you can control the flow through the unit, like Trigger Systems Ruby Elite. This style of refugium tends to be one of the most efficient. Read More »

Tadpoles in Aquariums – Watching the Miracle of Metamorphosis

Frog EggsI can remember foraging in ponds and puddles as a kid, especially once it got warm enough in Spring  that the ground was thawed and everything would reappear after a long winter dormancy. How could I not be fascinated by the frogs hidden at the water’s edge and the newts and salamanders I’d find under moist rocks and rotting wood? But what would really grab my curiosity and attention would be the various jelly-like egg masses that would appear along the water’s edge, speckled with black dots and begging to be observed. It was on more than one occasion that my siblings and I gathered a cluster of eggs in a jar to take home for observation. If you have a small spare aquarium and a few other simple pieces of equipment, you can raise amphibian eggs, too, and watch them change from a speck in an egg to a fully developed frog or salamander. Watching tadpoles in aquariums is a great educational project for kids and adults!

If you have a spare 5 or 10 gallon tank lying around or a small garden or patio pond, prepare to be amazed! Start by filling the tank or pond with clean water. Ideally you’ll let the water cure for at least a day or two, particularly if you have chlorinated municipal water, but you can also use a dechlorinator to make the water safe. Your tadpoles absolutely depend on having fresh, clean water for proper health and development. You’ll be bringing a small amount of source water with you from wherever it is you collect your eggs, but chances are you won’t be carrying several 5 gallon buckets of it back with you. Take care to have an environment prepared for your egg cluster before you bring it home.  Don’t put eggs into an occupied aquarium, keep them safe in a separate vessel.  Read More »

Australian Rainbowfish – the Natural Diet of a Popular Freshwater Fish

Many years ago I established a school of 75 Boezeman’s Australian Rainbowfish (Melanotaenia boesemani) at the Bronx Zoo.  The exhibit, which they shared with mangrove snakes, land crabs and crayfishes, made for a stunning display.  And although the building also housed proboscis monkeys, marsh crocodiles, hornbills and other impressive beasts, the brilliantly-colored Rainbowfishes drew a great deal of attention from visitors.

But many keepers become disappointed when, after a time, their fishes’ fading colors do a disservice to the “rainbow” part of their name.  Based on experience with related species, I’ve always provided my Rainbowfishes with highly varied diets, in which insects were heavily featured.  Those under my care have usually retained their bright colors, and breeding has been consistent.  A recent study that examined the natural diet of wild Rainbowfishes seems to bear this out, and has important implications for the care of other species as well.

Duboublay's rainbowfish

Uploaded to Wikipedia Commons by Roan Art

Terrestrial Insects: an Overlooked Food Item

My lifelong observations of captive and free-living fishes have led me to conclude that land-dwelling insects play an important role in the diets of many freshwater fishes.  As anyone with a pool or outdoor pond can imagine, untold numbers find their way into fresh and marine waters each day.  In 2009, the research of National Oceanographic and Atmospheric Administration biologists revealed that terrestrial insects comprise up to 100% of the diets of some US fish species. You can read more about this topic in the articles linked below. Read More »

Aquarium Salt Mixes – Choosing the Right Salt for Your Tank

Juvenile Queen AngelChoosing the right aquarium salt mix to add to your tank can be can be a confusing process, especially if you’re new to the hobby. But, it isn’t as complicated as it may seem, you just need a little background info to get you on the right path to choosing the salt that is appropriate for your set-up.  

Salt in Freshwater Aquariums

Adding salt to a freshwater aquarium is not a necessity, but it is used by many aquarists as a treatment to add electrolytes to the aquarium water, and as both a stress reducer and a parasite deterrent. Basic Aquarium Salt is not the same as the formulated mixes used to make a brackish or saltwater aquarium. Aquarium Salt is simply Sodium Chloride, and does not contain minerals and trace elements like calcium and iodine like sea water mixes. Adding small portions of this salt can help to treat osmoregulatory stress, an imbalance or disruption in the exchange of salts and minerals between the fish itself and its environment. Stressful situations such as transport, disease, or injury can cause osmoregulatory stress, but if used properly, aquarium salt can increase blood and oxygen flow through the gills, helping the fish relax and heal. When used in higher concentrations for short time periods as a dip or bath, salt can help to build a the protective slime coat on the body, preventing parasites from attaching and even killing one-celled parasites like Protozoa, that may already be on the fish. While aquarium salt does have some benefits, it is not a necessary additive. Once introduced to the tank, salt does not evaporate out of the tank. It can only be removed with water changes and plants, inverts and other sensitive species may be negatively impacted if the concentration is allowed to rise. Read More »

GloFish – It’s All in the Genes

Electric Green Tiger BarbsGloFish are some of the most popular, colorful and controversial fish to enter the aquarium trade in a long time. Their easy care, small size, peaceful nature and neon bright colors make them appealing to aquarists of all ages, but the modifications that cause these bright colors cause some debate among aquarists, scientists and environmentalists alike.

The original “GloFish” were not created for the aquarium trade. They came from a popular fish used in many different fields of research, the Zebra Danio (Danio rerio). Zebra Danios have been used in research for environmental studies, cancer research, genetics, reproductive biology, neuroscience and applications to other fields as well. They even made the trip to space in 1975 on the Russian “Salyut 5” space station. So what makes them such good research subject? Zebra Danios are easy to breed and it only takes hours for the internal organs to develop after the eggs have been fertilized (about 24-36 hours, depending on temperatures and conditions). During this time, it is easy for researchers to monitor the development of the embryo since the “shell” around the eggs is a clear membrane. The eggs can hatch about 12-36 hours after that (again, depending on the conditions). These variable time frames also mean that, while the development is being studied, conditions can be adjusted to slow down or speed up the development, depending on what exactly the researchers are trying to determine. The genetic sequence involving the structure of the Zebra Danio’s DNA and RNA is very well-known at this point and is comparable enough to our own that, by understanding how changes in this structure affect the fish, researchers are gaining more understanding into how changes in our genetic structure can affect our own health.

Originally, GloFish were being developed for two major fields: cancer research and pollution detection. In the late 1990’s/early 2000’s, researchers thought to develop a fish that would change colors when a certain pollutant was found in their water. The thought was to develop a fish that would appear normal in “ideal” conditions but when a specific chemical or type of chemical was present in the water, a “trigger” would be set off to cause the fish to “glow” with a fluorescent protein in their bodies. As a step in this direction, they began to develop a fish that would always have this flourescent “glow” in a reproducible and hereditary way that wouldn’t affect the ecosystem around them. To do this, scientists turned to a fluorescent protein naturally found in jellyfish, corals and anemones rather than potentially harmful chemical dyes. Around the same time, similar projects were using a fluorescent protein to “mark” specific genes that were thought to be a cause or sign of cancer. By pairing the fluorescent protein with the cancer-related gene, researchers could see the fluorescence increase or decrease along with the other gene and see if an increase or decrease in that gene was related to the cancer. Since the genes (and cancers) in these fish behave in much the same was as they do within ourselves, researchers are using this to develop a way to track, diagnose and treat cancer in people. Read More »