for the week of 8/6/98

There is probably no single tip that improves the chance of success with tropical fish than, Avoid Stress.” When fish have to deal with stressful conditions, they can quickly lose vitality and become more susceptible to infection or other illness. Here are some common sources of stress:

  • Changes in water temperature. A drop of more than 3 degrees fahrenheit over a 24 hour period often weakens fishes’ resistance to the common parasite, “ich.” A good quality, well maintained heater is a lifesaver.
  • Changes in pH. Rapid changes in pH can cause irritation, even if within the “acceptable” range of that species. When transferring fish or adding pH adjusters, avoid a shift of more than .5 (e.g. from 7.5 to 7.0) in a 24 hour period.
  • Changes in salinity (saltwater). Marine fish and invertebrates achieve a sort of balance between the water inside and outside of their bodies. A sudden change of .005 (e.g., from 1.025 to 1.020) can cause instant death in certain shrimps, and stress in other organisms.
  • Ammonia/nitrite toxicity. Mostly a problem during the “break-in” cycle, high ammonia levels can cause considerable damage to gills and nitrites reduce the blood’s ability to carry oxygen. See our other articles on New Tank Syndrome.
  • Inadequate aeration. Would you feel comfortable if the air around you contained only half as much oxygen in it as it should? This is a very real concern in aquariums. Keep the bubbling and surface agitation cranking and don’t overcrowd the aquarium with too many oxygen-sucking critters.
  • Rough handling. Carelessly netting and bagging fish can not only injure them visibly, but chemicals they produce while in a state of panic can harm them as well. Be patient and careful.
  • Aggression. A fish that is continually harassed or even just intimidated by its tankmates will inevitably lose its resistance to disease – and may even infect others on its way out!

“Tip of the week” appeared regularly in 1999 and 2000.