Aquarium Undergravel Filter

The undergravel filter is considered by many to be the most effective type of filter because it provides a high level of biological filtration. This filter consists of a plastic plate that sits under the gravel of the tank. Water is drawn through the gravel by pumping air to the bottom of the filter with an external air pump. Some undergravel filters are driven by powerheads mounted on the intake tubes. Both kinds provide excellent water circulation and aeration.

In essence, this filter uses the aquarium gravel itself as the filter media. Thus, very little mechanical filtration is involved and chemical filtration is completely lacking. The undergravel filter relies chiefly on the establishment of a healthy bacterial colony in the gravel. For this reason, certain kinds of gravel are required for this filter, and a longer setup time of many weeks is necessary to establish bacterial colonies. However, once a healthy filtration system is established, this filter can be used for months without intense maintenance and cleaning.

Although this system provides the most valuable kind of filtration, it may be the most complicated for the beginner. Excessive debris in the aquarium can clog the filter bed and must be routinely removed. Aquarists who want to maintain live plants will find that this filter will destroy root systems. In addition, fish may disturb the substrate and upset the filtration bed. The novice would be better off with an external power filter.

Aquarium External Canister Filter

The external canister filter is the next step up in power filters. This filter is much larger than the others and is designed to filter large tanks of 50 gallons or more. The canister filter is composed of a large jarlike canister, which generally sits next to the tank. It contains filter media and activated carbon, like the other filters, but has a much more powerful motor for filtering large amounts of water. Water is drawn up by an intake suction line and sent back to the aquarium through a return line. If the return line is properly positioned, water circulation can be provided by these filters. I only recommend this kind of filter for the aquarist with a larger tank.

Aquarium External Power Filter

The external power filter is the easiest and least complicated filter system for the beginner’s aquarium. These filters provide all three kinds of filtration and are specifically designed to turn over large amounts of water. The external power filter hangs on the side of the tank and is powered by its own motor. Water is drawn into the filter by a U-shaped siphon tube. it passes over layers of fibrous filter material and activated carbon and is returned to the tank via a gravity trickle system or a return pipe. Like the box filter, the power filter circulates the water, providing aeration.

While it works on the same premise as the box filter, the power filter is much more efficient at removing waste and debris from the tank. It does not need to be cleaned as frequently as the box filter. Many models have special filter cartridges that make cleaning these filters extremely easy. In addition, various types of cartridges can be purchased to chemically alter water quality and correct water chemistry problems.

Aquarium Internal Box Filter

As the name implies, the internal box filter sits inside the aquarium. An external air pump drives air through the box, drawing water from the aquarium through fibrous filter media and activated charcoal. Layers of filter media provide mechanical and chemical filtration, as well as adequate substrate for biological filtration. Since it is driven by air, this filter circulates and aerates the water.

In my opinion, the box filter does not provide adequate levels of filtration for the average aquarium. Aquarists who start with a tank of 20 gallons or more should not use this type of filter system. It is simply too small to handle the waste and debris that accumulate in the tank, and it has to be cleaned frequently.

Aquarium Air Hose

Your air pump and airstones require an air hose to link the two. This is plastic tubing that delivers air from your pump to the airstone. This should fit snugly at all joints so air does not escape from the system. Air leaks reduce the efficiency of the system (filter and airstone) and may ultimately burn out the pump. Make sure the tubing is manufactured for use in an aquarium; other grades may be toxic to fish.

If you intend to run multiple airstones or additional devices, such as filters, from a single pump, you need one or more air valves. These enable airflow to be directed to multiple devices from a single pump. Using several air valves enables you to turn devices on and off as you like.

Aquarium Airstones

An airstone is generally made of porous rock that allows air to pass through it, splitting the airstream into tiny bubbles. Too fine a mist will cause bubbles to adhere to various tank decorations and to fish. You want the bubbles to slowly travel to the surface and agitate the water. Commercially manufactured tank decorations that act as airstones can be purchased at almost any aquarium supply store.

Aquarium Air Pumps

There are two general air pump designs: the diaphragm type and the piston type. The former is much more common and generally provides enough maintenance–free use for the beginner’s aquarium. The piston pump, however, is more powerful and should be used in larger aquariums, particularly if an undergravel filter and multiple airstones need to be powered. The size and power output of air pumps vary. Consult your local dealer to match your aquarium with the proper air pump.

Aquarium Aeration

Fish need to have a lot of oxygen available for respiration. So, although most filters provide water circulation and aeration, it is a very good idea to have an external air pump moving air through one or more airstones in the tank. This is especially true for tanks that are at their fullest carrying capacity. The air pump increases circulation in the tank, promotes oxygen exchange at the surface, and increases the escape of carbon dioxide, carbon monoxide, and free ammonia from the tank. This increase in circulation also acts to mix all the aquarium levels so that a uniform temperature is maintained throughout the tank.

Aquarium Thermometer

To maintain the temperature at suitable levels, all aquarists need an accurate thermometer. There are basically two types of thermometers for the aquarium: the internal floating or fixed thermometer and the external stick-on thermometer. The internal ones tend to be more accurate, and the external ones tend to read a couple of degrees too low.

I recommend two thermometers to enable you to carefully monitor your aquarium temperature as well as to compare the accuracy of each unit. Don’t cut corners when it comes to maintaining water temperature. This piece of equipment is very important, yet it does not cost a lot.

Aquarium Heater

Based on their temperature preference, fish can be grouped into two general categories: temperate and tropical. Temperate fish include many species that inhabit cooler waters. However, the fish most commonly seen in freshwater aquariums belong to tropical species. The term “tropical” refers to natural habitats where the waters are warm throughout the year. It should come as no surprise, then, that it is necessary to maintain your aquarium within a specific temperature range. This is the job of the aquarium heater.

This essential piece of equipment maintains your tank at a constant temperature, regardless of the room temperature. With the exception of a few fish, such as the common Goldfish, the species you are likely to keep as a beginner will require the aquarium temperature to be maintained at 75 to 79 degrees Fahrenheit (24 to 26 degrees Celsius). However, this is entirely dependent on the species, and you should consult your local aquarium dealer or one of the many fish encyclopedias for specific temperature requirements. Obviously, you should not mix species that have very different temperature requirements.

There are a few types of aquarium heaters available to the aquarist, but the most common is the submersible glass tubular heater with a built-in thermostat. This heater attaches to the side of the tank and has external controls. Once it is properly set, it automatically responds to changes in water temperature and turns itself on and off. If you choose one of these, I recommend that you double-check the accuracy of the dial with a thermometer.

In general, you should place your heater close to an area of high circulation so that heated water can be rapidly and evenly distributed throughout the tank. This is usually near the filter system or the airstones.

Heater size largely depends on the size of the aquarium. The general rule is 5 watts of power for every gallon of water. Thus, a 20-gallon tank requires a 100-watt heater. Many fishkeepers recommend that two heaters be used in aquariums over 50 gallons; this allows for more even distribution of heat in the aquarium and also maintains correct temperature if one heater fails. The total required wattage should be divided between the two heaters (so a 50-gallon tank would require two 125-watt heaters, for a total of 250 watts).

Aquarium Ph

When we talk about pH, we are really referring to levels of hydrogen ions in solution. Ions are simply atoms with an electrical charge. These hydrogen ions have a positive charge. We measure the number of hydrogen ions on a pH scale.

The pH scale tells us how many hydrogen ions are in your aquarium water and, therefore, how acidic it is. It ranges from 0 to 14. While you would anticipate that a higher number on the scale would mean more hydrogen ions and a more acidic solution, this is not the case. In reality, a lower number on the scale means more hydrogen ions. A pH of 1 is very acidic, pH of 7 is neutral, and a pH of 14 is very alkaline, which is the opposite of acidic. This scale is logarithmic, which means that each number is ten times stronger than the preceding number. For example, a pH of 2 is ten times more acidic than a pH of 3 and one hundred times more acidic than a pH of 4.

The pH of your aquarium water is influenced by a variety of factors, including the amount of carbon dioxide and fish waste in the water. In general, the beginner’s aquarium pH should be between 6.5 and 7.5. Commercial test kits that are very simple to use are available at most aquarium supply stores. The pH level in your tank should be monitored every week or two to detect any changes. An abrupt drop in pH may be indicative of an increase in carbon dioxide or fish wastes. An increase in aeration or a partial water change may alleviate the problem.

There are ways to chemically alter the pH in an aquarium. However, unless you are attempting to attain specific pH levels that are dictated by the special needs of certain species of fishes, I do not recommend that you use them.

The Hood

An essential item for any aquarium is a hood or cover. This important piece of equipment performs a variety of functions. First, it prevents unwanted items from entering the tank and injuring the fish. Second, it prevents overzealous fish from jumping out of the tank. Remember, a fish cannot breathe air, and nothing is worse than finding your pet on the floor next to the aquarium in the morning. The cover also prevents water from splashing the walls and floor, causing damage, and it slows the rate of water evaporation from the tank. Water condenses on the cover and re-enters the tank instead of evaporating; this reduces the necessity of adding more water. Fifth, the hood helps the aquarium retain heat. And finally, the hood keeps water from damaging the aquarium light and prevents a potentially dangerous electrical problem.

The hood is generally fitted to the dimensions of the tank and is adjustable to allow for aquarium accessories. It should be composed of thick (1⁄8-inch) glass or plastic so it can support the weight of other aquarium components if necessary. It should be segmented so the entire assembly need not be removed to feed the fish or work in the tank.

For the beginner, I strongly recommend the type of hood that also contains the aquarium light. These units are self-contained and are designed to keep water from the lighting unit, minimize danger, and cover the entire tank. If possible, the tank, stand, and hood should be purchased as a package from a single manufacturer. This prevents the problem of mismatched aquarium components, and may also be less expensive.

The Aquarium Stand

The best support for the heavy weight of the aquarium and all its components is a commercially manufactured aquarium stand. This type of support is built to hold a full aquarium. Homemade stands and other furniture may look sturdy, but can fail under the heavy load. Stand failure can be costly to the aquarist and the homeowner (and the fish), so don’t try to save money on your aquarium stand.

If you don’t buy a commercially built stand, I recommend that you place under the tank a 5⁄8-inch sheet of plywood and a 1⁄2-inch sheet of polystyrene cut to the dimensions of the tank. These layers will even out any imperfections in the supporting surface and distribute the load of the tank.

The Right Fish Tank

The general rule is to buy the largest aquarium you can afford and can accommodate in your home. The reason for this is fairly straightforward: Fish require adequate space to swim and sufficient oxygen to live; both are dictated by the size of the tank. The oxygen content of water is related to the surface area of the tank and the temperature of the water. Warmer water has less oxygen than colder water. Since most freshwater tropical fish prefer water warmer than 75 degrees Fahrenheit, the amount of oxygen in the tank may be limited. The more surface area a tank has, the more room for gas exchange at the surface more opportunity for oxygen to enter the water and toxic gases to leave. Therefore, the larger the surface area of the tank, the more fish the tank can hold.

Several different methods have been used to determine fish capacity, and there are several general rules. In my opinion, it is better to err on the side of too few fish than too many fish. Most aquarium enthusiasts use fish length and tank volume to estimate the number of fish an aquarium can hold; larger fish consume more oxygen and, therefore, require more aquarium space. The general rule is 1 inch of fish per 4 gallons of water for the first six months. You can gradually increase fish density to 1 inch per 2 gallons after this initial period. For example, a 40-gallon aquarium should contain no more than 10 inches of fish for the first six months. These may comprise ten 1-inch Neon Tetras or five 2-inch Oscars. After six months, additional fish may be added gradually to increase the total number of inches to 20.

Keep in mind, however, that fish grow, and your 2-inch Oscar may be 3 inches after those six months. Also, realize that this general rule does not compensate for the shape of the fish. The width of a fish is called its girth. The girth of an Eel is much smaller than that of an Oscar, and the 3-inch Eel is likely to require less space than the 3-inch Oscar, so the general capacity rule does not apply. If you plan to keep heavier fish (fish with a greater girth), be more conservative in your tank capacity calculations.

Because surface area is so important to the capacity and health of your aquarium, long tanks are much better than tall tanks. Even though both tanks may hold the same volume of water, the upright (tall) tank has much lower carrying capacity of fish because of its smaller surface area.

Once you have decided on the appropriate size of your aquarium, choosing the tank itself is very straightforward. Home aquariums are made of rectangular glass plates sealed with a silicone rubber cement, or of molded acrylic; both have their ups and downs. Glass aquariums are the most common and practical aquariums to buy, and I recommend them for the beginner. They are built for the sole purpose of housing living animals and are, therefore, nontoxic. Glass does not scratch as easily or yellow as acrylic does.

Aquariums with plastic or metal frames are sometimes available, but I have found that this design is not as aesthetically pleasing and that the frames are unnecessary. When choosing your tank, be sure there are no scratches on the glass and that there are no gaps in the silicone that can cause leaks.

Fish Breathing

Among the most primary of the basic needs of fish is oxygen. Like land animals, fish require oxygen to live. However, fish must derive oxygen from water and special respiratory organs, called gills, enable them to do so. The gills of a fish are analogous to our lungs: They supply oxygen and remove carbon dioxide from the blood of the fish. Then, oxygen is transported by the blood to the tissues where it is used to produce energy.

Most fish have four gills on each side of the head, protected by a single gill flap, or operculum. When a fish breathes, water is taken into the mouth and passed over the gills and out the operculum. As water passes over the membranes and filaments of the gills, oxygen is removed and carbon dioxide is excreted. To accomplish this, the gills have a very high number of blood vessels that deliver the oxygen to the rest of the fish via the blood.

Fish Feeding

Just as a fish’s body shape can tell you a lot about its swimming habits, its mouth can tell you something about its feeding habits. Bottom feeders have downward pointing mouths, while surface feeders have mouths that point upward. For most fish, the mouth is at the end of the snout.

The size of the mouth is usually directly related to the size of the fish’s preferred food. For example, large predatory fish like Oscars have larger oval mouths for consuming smaller fish. Fish that normally feed on small aquatic invertebrates, like Neon Tetras, have smaller mouths. Some tropical freshwater fish have specialized mouths for specialized feeding strategies. Plecostomus fish, for example, have special sucking mouths for bottom feeding.

Freshwater tropical fish have a relatively straightforward digestive system, which varies from species to species. In general, food passes from the mouth, down the esophagus, to the stomach, and through the intestine; wastes are expelled from the anal vent. However, several species lack true stomachs and instead have elongated, super-coiled intestines.

Fish Swim Bladder

As mentioned earlier, living in the dense medium of water presents a few problems for fish, and one of these is buoyancy. Maintaining a certain level in the water column without having to expend a lot of energy is very important to fish. Therefore, most species have a special organ called the swim bladder. This gas filled sac, located in the abdominal cavity of the fish, acts as a life vest, keeping the fish at the correct level in the water column.

There are many types of swim bladders. The Trout has a simple single chambered sac, the Goldfish a two-chambered type, and the Angelfish a three chambered bladder. Different species also use different methods to fill the swim bladder with air. Some have a direct connection between the esophagus and the bladder and simply swallow air to fill it. Others must rely on gas exchange from specialized blood vessels in the circulatory system to fill the swim bladder.

In addition to its role in buoyancy control, the swim bladder helps to mechanically amplify sound for better hearing in certain species of fish.

Fish Scales

The bodies of most tropical fish are covered with scales. The scales are composed of a hard bony substance and serve to protect the fish, reducing the chance of injury and infection. Covering the scales is a very thin layer of epidermal (skin) tissue that contains mucous cells. These cells produce the slime that we normally attribute to fish. The mucous coating not only protects the fish against injury and infection, but also helps the fish to swim more easily in the water, reducing friction between the body and the water.

The scales of a fish are actually translucent, like glass, and lack color. The vibrant colors of tropical fish come from specialized pigment cells called chromatophores in the deeper dermal layer of the skin. Fish that are clear, like the Glassfish, lack these pigment cells. The color of the fish depends on the types of chromatophores present. There are generally three types of chromatophores in fish: melanophores give fish the darker colors of black, brown and blue; xanthophores produce red, yellow, and orange; and iridophores reflect light, producing a silvery shine common to many fish.

Fish Fins

All species of fish have fins in one form or another. The fins are critically important appendages that enable the fish to propel, stabilize, maneuver, and stop itself. In some cases, fins have developed to protect the fish as well. Again, depending on the type of fish and the habitat it lives in, the fins can take on many shapes and functions. Bottom, sedentary, or slower moving fish typically have rounded fins, while faster, open water fish generally have longer, pointed fins.

Fish fins are either paired or unpaired. The only fins that come in pairs are the pectoral and pelvic fins, while the dorsal, anal, and caudal fins are unpaired. The pectoral fins are the paired fins closest to the head. The fish uses these fins to stabilize, turn, maneuver, hover, and swim backwards. These fins are generally found just behind or below the gills on each side of the fish, under the midline of the body.

The pelvic fins are also paired and vary the most in position. In some fish, they lie under the fish toward the rear. In others, such as many tropical species, the pelvics are closer to the head under the pectorals. In general, the pelvic fins act as brakes while aiding in stabilizing and turning the fish.

The dorsal and anal fins are unpaired fins that are found protruding from the top and bottom of the fish, respectively. Dorsal fins may be elongated or short, elaborate or simple, singular or multiple. In some species of fish, the dorsal or anal fin may be completely lacking. Both fins help stabilize the fish and keep it moving straight.

The caudal or tail fin is a single fin largely responsible for propelling the fish forward. This fin can also assist in turning and braking. Faster fish have deeply forked caudal fins, while many deep-bodied and bottom fish have square or rounded tail fins.

In general, the main supporting structures of fish fins are soft rays. However, anyone who has handled a fish knows that the dorsal, anal, pectoral, or pelvic fins of many species also have spines. These sharp, bony structures provide protection against predators and can certainly hurt us as well.

Fish Body Shape

A great deal can be learned about a species of fish by looking at its body form or shape. Fish that are streamlined or bullet-shaped, like Neon Tetras, are well adapted to the open waters of freshwater lakes and ponds. On the other hand, flat or stocky fish, like Catfish, typically live on or close to the bottom.

Fish Evolution

The group of aquatic animals that we call fish has evolved over 400 million years to be the most numerous and diverse of the major vertebrate groups (animals with backbones). Fishes have permeated all the waters of the world, adapting with an incredible variety of forms, lifestyles, and behaviors. From seasonal freshwater streams, desert springs, and salty bays to coral reefs and the deep abyss, different species of fish have found and created niches for themselves. There are well over 20,000 known species of fish that currently inhabit the earth, and many are discovered every year.

Since salt water covers more than 70 percent of the earth’s surface and fresh water only 1 percent, one would expect that there would be many more marine (saltwater) species than freshwater species of fishes. Actually, 41 percent of the world’s fishes inhabit strictly fresh water. Although quite similar in many ways to their marine counterparts, freshwater fish have adapted to a much wider range of habitats and a greater variety of water conditions. Hence, freshwater fish are typically hardier than their marine friends and much easier to maintain. That’s good for you.