Thursday, July 21, 2005

Filtration Methods For The Discus Tank

Good filtration is the prime priority in the discus tank. Basically, there are three types of filtration - mechanical, chemical and biological. Let's start with the basics...

Mechanical filtration removes the uneaten food, waste products and acumulated plant waste from the tank. Different methods will accomplish this - pads, sponges, and floss, to name a few. The objective here is to capture the dirt before it pollutes the tank to high levels. Common filter floss is inexpensive, and highly efficient, making it a good medium for the tank filter. One must keep in mind, however, that the function of the mechanical filter is basically aesthetic.

Filtering using chemical filtration takes place at the molecular level. The most commonly used medium is activated charcoal. Activated charcoal adsorbs a huge amount of pollutants in the tank, and discoloration,antimony, arsenic, chlorine, chloramine,chromium, hydrogen peroxide, potassium permanganate,phosphate plus some of the heavy metals and other toxins in different degrees. (adsorbs: Formation of a thin film on a surface.) It does not, however, remove ammonia, nitrite or nitrate, so don't expect it to do the job of biological or mechanical filtration. If your tap water is overly high in phosphates or nitrates, there is the chance that your fish won't do well until you pretreat the water with activated charcoal or other specific resins. If you live in the city, chances are good that the city can provide you with an analysis of their provided water. If, however, you live in the country, and have your own well, then the water should be sent to a lab for testing.

Activated charcoal can produce crystal-clear water, but the downside of this is that one tends to rely on the activated charcoal to cover up sloppy maintenance. It should be used as a back up only, and you should not be dependent on activated charcoal to keep water safe and clean for the Discus. Frequent water change is the only real insurance you have of keeping your Discus safe and in good health.

I have saved biofiltration for last because it is the most important aspect of a good environment for Discus. Without good biofiltration practices, your Discus will not survive. Mechanical and chemical filtration results can be seen visibly - the tank just looks cleaner. Even though chemical filtration does remove some of the toxic materials from the water, it takes biofiltration to make the water safe for habitation.

Cycling a tank is a practice that reproduces the nitrogen cycle in the aquarium.
In the aquarium, we need beneficial bacteria, which are known as nitrobacters. Stress Zyme is a well known brand of bacteria strain used in aquaria. These "good" bacteria colonize the filter media and every surface of the tank. The most beneficial of these bacteria is Nitrosomonas sp. which consumes the toxic ammonia that is produced by decomposition of fish waste, plant matter, and uneaten food. In the Nitrogen Cycle, the ammonia is reduced to nitrite. The nitrite is then consumed by Nitrobacter sp. and is reduced to nitrate, which is the least toxic end-product of nitrification. The nitrate is then removed from you system by a regular water-change regimen.

Maintaining a healthy bacterial colony in the biological part of your filtration system is quite simple if care is taken to not destroy the colony. When cleaning the media, use only tank water. Never use hot water or fresh tap water to clean the sponges or media, but instead gently rinse and carefully wring out excess water in a pail of tank water. The goal here is to maintain the highest rate of bacteria as possible on the media.

It is possible that your biological filter will crash if the aquarium is left without power for a day. The bacteria are without oxygen for a period of time which will cause them to die, your fish will be gasping for breath, and a foul smell is encountered in the tank. Never simply turn the filter back on! this will flood the aquarium with toxins, and the media must be replaced if a crash occurs.

Following these simple principles will help to insure that your Discus have a happy and safe environment for many years. Again, there is no subistitue for regular water changes, but by following these simple rules, chances of survivial of the Discus are much higher.

Wednesday, July 20, 2005

Tank Requirements For Discus

For Discus fish, there are 2 consideration in tanks - tank depth and volume. Because of their size and swimming habits, a minimum of 18" is needed for tank depth, the deeper the better. Regarding volume, a good rule of thumb is that each adult discus will need 10 gallons of water. Larger tanks will also give more stable water conditions, and taking into account other considerations the minimum size for a discus show tank should be no less than 55 gallons. It is also advisable to use a rectangular tank. Not only are they cheaper, but are more efficient, because they maximize surface area. Surface area is the most important factor in buying a tank. Why? Because it is only at the surface of the tank that gas exchange occurs. (Oxygen in, Carbon dioxide out.) Assuming you have a seventy five gallon show tank, and it's biological filter is working as required, up to twenty young fish 3 inches in size, or 6 or 8 fully adult discus can comfortably inhabit the tank. An outside filter may be added to large tanks to increase basic aeration and biological filtration needs.

Keep in mind that when young discus fish are small,they grow fast and become quite large in a short period of time if fed well and water quality is maintained. If your tank is too small they will not be happy and it will quickly stunt their growth. Juvenile discus should not be kept in overly large tanks. Being a social fish, Discus tend to become very skittish in large tanks. In our hatchery, we place 6 Discus up to 1.5" in a 29-gallon tank. They will be moved tp larger tanks when they get to 2.5", and show possible signs of "pairing off". Always try to buy the largest tank you can afford for discus fish.

If breeding Discus is a consideration later on, tanks can be down sized to twenty gallons per pair. At our hatchery, 29 gallon rectangular glass tanks are utilized for every breeding pair.
A bare bottomed tank with at 2 ½ gallons of water per inch of fish, a couple of sponge filters and a canister filter with activated carbon in it is used to begin the process. This is maintained at 6.6 - 6.8 PH, and the temperature is set at 82 to 84 degrees F. We make 50% water changes weekly, and some breeders will go as high as 95%. Optimal results would be achieved with a 15% water change daily. Because Discus produce slime on their body, and it is shed regularly,it coats the inner surface of the tank and promotes bacterial growth. A safe bet is to wipe down every discus tank every week. There are commercial sponges and brushes available to do this chore.

Because Discus are large fish, they require clean water and proper filtration. The tank must be "cycled" and tested for nitrates/nitrites before placement of Discus in the tank. Our policy is to use fish such as some of the more common cichlids to "cycle" the tank. A good rule of thumb here is to wait at least 4 weeks before attempting to place Discus with the "cycling" fish. If you are active in the aquarist community, a friend might possibly loan you some "cycling fish" to begin your project, and the "cyclers" can be returned to their owner upon completion of the cycle.

Discus prefer soft water, due to the constant rainfall and run-off in their natural habitat. We are more concerned, however, with cleanliness. It is much better to have a high quality of hygiene in the tank than it is having optimal water conditions, though we strive for both. Discus will adapt to most conditions, including PH up to 7.8 and 350-ppm microsiemens of hardness, but cannot survive in constantly changing water conditions or dirty water.

Tuesday, July 19, 2005

Cichlids for Dummies

cichlids for dummies

In a previous article, I reported on the ingenuity of Nick, my partner in our new fish hatchery.

Now, Nick has come up with a great idea -- and a new blog -- for an egg tumbler.

Nick is a good resource on all things Cichlids, and I rely heavily on him for information. Check out his article, and his new blog...


Monday, July 18, 2005

An Experiment in PH Levels (revisited)

Because it is imperative that discus fish have optimal water conditions, much has been written about this subject, This is the plan put in place to insure proper PH water levels in our hatchery.

Allnut Enterprises' breeder, Nick Lockhart of Noblesville, Indiana, has many ingenious ideas as to how to accomplish things in the hatchery. We begin our experiment with two matched pairs: two red melons, and two leopardskins. They are lovely, friendly fish, and have been getting acclimated to our tanks and the aquarist since the end of June.

Initially, we begin to prepare for the new arrivals by setting up the tanks in this manner: water was tested for PH and nitrite levels, and a proper ecosystem for active bacteria was begin by populating the tank with cichlids that Nick has been raising prior to the purchase of the discus. When we felt that the water/bacteria levels were correct, we set up the meeting with the breeder, and made the trip to Bloomington, Indiana.

Upon arrival at home base with a travel time of about an hour and a half, we immediately begin to acclimate the pairs to their new home. We were advised by the breeder to let them acclimate to the new tank water by "floating" the bags containing the fish for approximately one hour to equalize the temperatures, and to add a cup of water to the bag from the tank to equalize PH levels.

We did not, however, follow this procedure. We took approximately six hours to acclimate by adding a cup of the tank water to the bag each hour, and keeping a close eye on the discus and PH levels, because they were stressed from the trip. A Hanna PH digital meter was used for testing, which gave us a very accurate reading. As large changes in PH in a short period can shock the discus, we were careful in this approach. Our water at the time matched the water in PH levels from the breeder closely.

Because the two pair were bought for breeding purposes, Nick was not comfortable with the PH level, which at that time was at approximately 7.5, high for optimal breeding conditions of 6.5-6.9. What to do?

We had read that hanging a mesh bag of peat moss would help to lower the PH, but were not happy with the idea of having debris from the Peat in our tanks, which are kept scrupulously clean. We knew there had to be a better way to accomplish this goal.

Because Nick lives in town, and has city water, he uses a Reverse Osmosis filtering system to insure that the water is free of chemicals and suitable for the aquarium. Knowing that Peat Moss will lower the PH in an aquarium system, and having a large bag left over from making culture for Grindal and White Worms, he took a 5 gallon pail, and drilled a series of holes around the perimeter of the bottom of the pail, using a 3/32" drill. He then lined the bottom of the pail with a think layer of regular aquarium filter floss, put a thin layer of gravel on top of the floss to catch debris, and topped that off with a thick layer of Peat Moss, with the finished pail being about two-thirds full.

The outlet hose from the RO system was then allowed to drain into this pail. Setting the pail over the top of the holding tank, the water slowly drained down through this medium into the holding tank.

Initial test of the recycled water showed a drop in PH to below the base of 7.0. We have been adding the water to the discus tanks slowly through water changes so as to not shock the fish, and at our business meeting this weekend, Nick informed me that the PH levels in the discus tanks are now at approximately 6.6, which is the optimal level for breeding discus.

Cost of the project? If you already are using an RO system, and have a holding tank, you will spend a twenty dollar bill getting the Peat Moss and filter floss. Not bad, considering a breeding pair of dicus can run you $425 dollars!