Caring for the Tank

 

 

TANK CLEANING

This applies mainly to tank maintenance after the fish leave the breeder basket. The most important job after the hatchlings are in place is to keep the tank system clean and the bacteria colonies growing and happy.

 

• Whenever possible, do your tank work without putting your hands or those of students into the water.

• If you need to put hands in the tank, wash hands in de-chlorinated water—trout are extremely sensitive to chlorine—to remove all contaminants (such as soap and lotion) and dry them thoroughly. Proper hand care when working in the tank will ensure a higher trout survival rate.

• Remove dead and sick-looking fish from the tank immediately. Some fish may start to get lethargic or have problems swimming. Eventually, they simply float around the tank or sink to the bottom, die, and decay. Even one dead fish, if left too long, can spread disease and endanger the whole population

• The gravel should be cleaned twice a week (e.g., Tuesday and Friday). Clean half of the gravel each of these days. During one cleaning, use the siphon to suck up fish waste and dirt from the non-gravel portion of the bottom of the tank and half of the graveled part of the tank.  Gravel is cleaned by moving the siphon through and under the gravel, sucking up water and fish waste trapped in and below the gravel. Use one of the 5-gallon buckets to collect the wastewater. Clean the remaining portion of the gravel in the tank during the next semi-weekly cleaning.

• Occasionally, fingerlings can get sucked up along with dirt from the gravel. Just net them and return the runaways to the tank. They may look dispirited or even comatose, but the odds are that they will survive.

• Only remove as much water as needed to clean the gravel and replace that water with water that has been treated with NovAqua Plus water conditioner. (See Appendix E for instructions.) As the fish grow, it may be necessary to increase the frequency of weekly gravel cleanings. Even though about 80% of biological activity takes place in the filter, gravel in the tank serves as part of the tank’s biological filter.

• Weekly remove the slime and dirt that accumulate on the sides of the tank, using a hand mitt, a long handled brush, or some other suitable implement. As the trout increase in size, bi-weekly cleaning of this sort may be required.

• Weekly examine the filter intake and remove tank debris, as well as any dead or trapped fingerlings found there.

 

B. MAINTAINING CHEMICAL BALANCE IN THE TANK

• Eighty percent or more of the biological activity of the trout tank takes place in the filter. The goal of the tank development process is to “seed” the filter with bacteria that play three different roles:

• decomposition

•  nitrification

• denitrification

 

​By maintaining a healthy water chemistry balance for trout,  the need for water changes is minimized.

 

High ammonia and nitrite levels indicate a lack of adequate biological nitrification. Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate. Check KH and add baking soda if required. Add 20 ml of Nite-Out II to the filter to increase ammonia removal. Nitrite and Nitrate are the byproducts of nitrification. Water changes are an additional method of correcting ammonia problems.

 

Be aware, however, that some short-term spiking of ammonia, nitrite, and nitrate readings is normal. Don’t over-react and increase the size and frequency of water changes unless an ammonia spike is accompanied by signs of fish distress. Almost certainly your fish, through their behavior, will tell you if your water chemistry is seriously out of balance. High ammonia and nitrite levels prevent fish from absorbing oxygen through their gills, at which time the gills darken and may take on a brown color. Fish will be seen at the surface gasping for air or swimming erratically. This is the time to take remedial action by adding 20 ml of Nite-Out II and performing a water change. But if your fish look good, if they’re eating and swimming normally, you might not need to do anything.

                                       

The ammonia drives the nitrification process of the Nite-Out II bacteria. Because our tanks typically contain more fish than is recommended for a 55-gallon tank, removal of fish and food waste by vacuuming the tank bottom should be a normal part of your and your students’ routine maintenance.

 

At the early stages of development, only 2-3 gallon water changes may be necessary. As your fish grow, and food portions increase you may need to change about 5 gallons of tank water at a time. The bacteria in your tank should provide the first line of defense against changes in your tank that affect water chemistry balance.  Water changes are secondary to biological activity. Allowing the bacteria to do their job will reduce your need for water changes. The log of daily water testing and the overall health of the trout will also help you determine how much water to change and when to do so.

 

Note: The ammonia test produces a value that consists of ammonia plus ammonium. The former is un-ionized (NH3) the latter is ionized (NH4+). Ammonia is hazardous to fish and plants; ammonium is not. The test reading is a measure of the sum of both. However, it does not indicate the percent distribution of each component. Therefore, if the test yields an elevated ammonia reading but the fish show no sign of distress, it is very likely ammonium is the larger component of the reading.  At lower temperatures (520-540F.) and pH between 7.0 – 7.8 the ammonium value predominates. Unless the fish show signs of distress, there is no need to panic if ammonia readings seem on the high side. At pH readings above 7.8, ammonia toxicity increases.

 

How temperature and pH affect ammonia

Ammonia varies in toxicity at different pH and temperature of the water. For example, ammonia (NH3) continually changes to ammonium (NH4+) and vice versa, with the relative concentrations of each depending on the water's temperature and pH. At higher temperatures and higher pH, more of the nitrogen is in the toxic ammonia form than at lower pH.

At what point should you get concerned about ammonia levels becoming a threat to your fish given that ammonia is constantly being produced? The answer to this question will depend on the temperature and pH of your tank water, how many fish are in your tank, and how much uneaten fish food remains in the system.

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This chart identifies the level of ammonia you can tolerate in your fish tank before it affects the fish. You will notice that at very warm water temperatures a small amount of ammonia can be toxic to your fish. At the opposite end of the spectrum in very cold water, the opposite is true. Fish can tolerate higher levels of ammonia the cooler the water. This is also true for dissolved oxygen. Cold water can store more dissolved oxygen than the same volume of warm water. The good news is that the water temperatures and pH levels at which our trout are raised tend to reduce the effect of harmful ammonia. If you encounter an ammonia spike that is causing fish mortality you may try lowering the water temperature 2-4 degrees to see if the fish start to recover. Example: 10° C = 50° F. At pH of 7.6, the ammonia test reading would have to exceed 2.8 ppm (interpolate between 3.2 ppm and 2.4 ppm) before it became significant.