Healthy Aquarium Inhabitants: Preventive Measures, Part Two

by | May 15, 2009 | 0 comments

Part one (Bartelme, 2009) of this two-part series covered preventive tips on the subjects of quarantine, stress, handling and selecting specimens for your aquarium. We continue here with tips on the subjects of acclimation, nutrition, good habits for aquarists and more.


If the pH and temperature in your quarantine system closely match those of the tank that your new fish came from, it should not be necessary to drip acclimate them. It is more important that the fish are removed from any toxins in the transport bag (i.e. ammonia) and placed into oxygenated water quickly.

Marine teleost fish adjust quite readily to a reduction in salinity so they can be placed immediately into low salinity water. However, they do not adapt quickly when exposed to a salinity that is much higher than they are used to. Do not expose sharks, rayfish, invertebrates, live rock or live sand to hyposaline conditions.

Quarantining fish in hyposaline conditions has several advantages. It is a proactive approach to dealing with some types of parasites, helps the fish regain normal homeostasis (balance) quickly, conserves metabolic energy, and it also helps them to maintain osmotic balance in the event of a wound or compromise to the mucus/scale/skin barrier. A salinity of 14ppt for thirty days is suggested (note the difference between salinity and Specific Gravity). The pH and salinity should be checked daily when administering hyposalinity therapy. It is important that the salinity is measured by a refractometer or other accurate device. Some hydrometers, especially plastic swing-arms types, are not particularly accurate. After the treatment is completed you can begin to slowly raise the salinity a couple of points a day until it matches your display aquarium.

Fish are most sensitive to rapid changes in the water parameters of temperature and pH. Ideally, acclimating fish to large variations in these parameters should be accomplished over a few days rather than in minutes or hours. Start by getting newly acquired fish into a quarantine system with a pH and temperature that is similar to what they are used to (provided these parameters are within safe limits). Then these water parameters can be adjusted slowly over a couple of days to match the display aquaria.

Since your fish has already been acclimated during the quarantine period to the pH, temperature and salinity of your display aquarium, the move into the permanent tank should be quick and relatively easy. When the day arrives to move your new acquisition into the display tank, place them in a clear plastic bag or container for about fifteen minutes. Placing the new additions in a see-through container, prior to release, gives curious tankmates an opportunity to examine them without exposing the newcomers to aggression. Move a few rocks or decorations to disorientate the established inhabitants and reduce aggression. Then feed the inhabitants right before releasing the new addition to divert attention away from it. You might also reduce the lighting intensity without making the tank dark.


Preserving Food Quality

Storing all freeze-dried and flake foods in a freezer will help preserve the nutritional quality longer. Purchase foods in quantities that will be used in two months or less and store all foods in freezer bags.


Feeding Variety

Sometimes people forget that fish need variety in their diets to stay healthy just like humans do. Offer a wide assortment of foods, especially in an aquarium with representatives from several different families of fish. Offer some plant-based foods first at each feeding, unless all of your stock is carnivorous. Dried seaweeds such as nori and foods such as Formula-Two™ and spirulina are good choices. An occasional feeding of frozen broccoli, romaine lettuce, or peas can be used. Some of the best foods can be found at the local seafood market where you can purchase clams, scallops, shrimp, fish fillets and other choices. Seafood of marine origin is preferable for saltwater fish. Freeze fresh seafood before use as a safeguard against parasites.


Offer Foods that Emulate the Natural Diet

Research the natural diet of each species prior to purchase and then offer foods that are as similar as possible. If the fish are carnivores then feed them meaty seafoods that emulate what they would eat in the wild. This may be fish fillet, shrimp, scallops, etc. Herbivores should receive a variety of plant based foods such as an assortment of algae. Omnivores need a combination of vegetation and meaty seafoods.


Feeding Frequency and Amounts

Feeding aquarium fish properly is more of an art than a science. You will have to experiment with the types of foods, the frequency of feedings and the amounts offered. Overfeeding is not good for the health of the fish or the water quality in the aquarium. Small and juvenile fish may need more frequent feedings than other fish. Grazers need an almost constant supply of foods. Some species of tangs are a good example of this. Keep a variety of dried algae on a clip so they can eat it during the day. Then remove what is left each day. In general, small frequent feedings that are eaten in just a few minutes are best.

Predators such as lionfish and groupers should only be fed about every other day. Resist the temptation to feed predators too frequently or give them too much food at any one time. Overfeeding can lead to impaction and internal bacterial infections along with other complications.


The Causes of Dietary Deficiencies

  • Improperly stored foods
  • Monotonous diet
  • Not using foods that are adequate substitutes for the natural diet
  • Not feeding often enough
  • Not providing enough food per feeding



Supplementing the diet with the addition of vitamins (i.e. Zoe™) and highly unsaturated fatty acids such as Selcon™ is good insurance toward guarding the health of your stock. These additives also assist fish in healing and recovery from stress. Refrigerate the supplements.


Immune System Stimulants

Beta glucan is a proven immune system stimulant for fish. It can be safely used in combination with any chemical or treatment. Adding a small amount of Beta glucan to the food during the initial quarantine period may help prevent the fish from getting sick. It is also useful when treating fish when they are ill (Bartelme, 2003). For further reading on Beta glucan see the link in the reference section at the end of this article.


Manipulating the Salinity

Reducing the gradient between the internal salinity of fish and their surrounding environment helps alleviate the physiological consequences of stress and it will help fish regain normal homeostasis more quickly after the stress of transport or handling (Wedemeyer, 1996). This is accomplished by raising the salinity (only slightly for freshwater species) for freshwater species, or reducing the salinity for marine (teleost) fish. Treating newly acquired marine fish with hyposalinity therapy is a proactive approach to some types of external parasites (Bartelme, 2004). The pH tends to fall in diluted saltwater so monitor this parameter closely. Do not use hyposalinity therapy with sharks, rayfish or invertebrates. Use caution when raising the salinity with freshwater fish that do not have scales or are otherwise sensitive.


Be Prepared for a Water Change

Keep a fresh batch of well aged and aerated water ready for any aquarium emergency. A large water change can help you overcome a plethora of problems and mistakes. Raw or just mixed saltwater is irritating to delicate gill tissues and stressful to fish. The water should mix for 24hrs or more prior to use to allow enough time for the water chemistry to stabilize and the salts to dissolve fully. A large food-grade Rubbermaid container with a heater and a water pump is perfect for storing a batch of saltwater.

Nothing is more important to the health of fish than maintaining good water quality. Make regular water changes using well aged and aerated water to help remove toxins and impurities. Water changes of about ten percent a week are recommended.


Use Caution when Medicating

Never medicate fish without first doing your best to make a probable diagnosis. You should be reasonably certain that you have identified the problem before taking action. Using medications can be stressful to the fish and possibly do more damage than good. Fish that are badly stressed are in a weakened condition. They should not be exposed to any unnecessary treatment or medication that will further weaken them or suppress immune function. Check all the water parameters and make a large water change to be sure that you are not dealing with a water quality issue before subjecting fish to drugs or chemicals.

Avoid formalin and freshwater dips with recently handled fish, because they have lost some of their protective mucus layer. Also avoid using these treatments on fish that have open wounds. It is not a good idea to use copper on fish that are already in a weakened state, because it suppresses immune function. When possible, wait for a week after handling before beginning any copper treatment to allow the fish time to recover better immune function.


Observe the Animals Daily

Behavior changes are often the first indicators that something is amiss. If you closely observe each animal for a few moments on a daily basis then you will quickly recognize any change in behavior. These changes may come well before water tests detect anything is out of line.


Continuing Education

One of the most interesting aspects of aquarium keeping is that there is always more to learn. There seems to be a never ending flow of new information as the hobby evolves. Never stop reading aquarium literature. Learning is a fundamental element of the hobby and should be an ongoing process. Review books that you have already read from time to time as a reminder of what you have learned. Join an aquarium club. Internet forums are also great learning tools where you can discuss various aspects of the hobby with other aquarists.



  1. Bartelme, T.D., “Tips for Healthy Aquarium Inhabitants: Preventive Measures for Aquarists, Part I.” Advanced Aquarist’s Online Magazine, January, 2009.
  2. Bartelme, T.D., “Beta Glucan as a Biological Defense Modulator: Helping Fish to Help Themselves.” Advanced Aquarist’s Online Magazine, September, 2003c.
  3. Bartelme, T.D., “News from the Warfront with Cryptocaryon irritans. Part Three of Five.” Advanced Aquarist’s Online Magazine, January, 2004.
  4. Wedemeyer, G.A. “Handling and Transportation of Salmonids,” Principals of Salmonid Aquaculture. Pennel, W. & Barton, B., eds., Elsevier Publishing, Netherlands, 1996.