Why are my fish dying with pink and green algae in their tank?

Related Answers from Veterinarians

• Answered By Angel Alvarado, LVT

  Licensed Veterinary Technician

  Published on November 18th, 2017

  Your tank may be overstocked which will contribute to excessive algae growth. Other causes include poor water quality, overfeeding, too much light and slow water current.
  Consider removing some fish to another tank or getting a larger tank. If you choose the latter, it will need to be properly cycled before you move fish. A general guideline is one inch of fish per gallon of water. Use the adult size of any fish you plan on keeping when estimating tank requirements.
  Put the lights on a timer. A photoperiod of 10-12 hours on and the remainder off should suffice. Increase filter flow if you can. Standing or slow moving water will promote algae growth.
  For now, you can use an algae scrubber to clean glass and tank furniture. Perform partial water changes and rinse filter media. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Use tank water, not tap water, to rinse filter media to preserve beneficial bacteria in the sponge.

  

  2Pet Parents found this answer helpful

• Answered By Angel Alvarado, LVT

  Licensed Veterinary Technician

  Published on October 11th, 2017

  Too much light can cause algae growth which will give a murky or cloudy appearance to a tank. Use a timer and set it for a 12hr on/off light cycle. Move the tank away from direct sunlight if necessary.
  Perform a 20-25% water change every week. Use aged or conditioned water that is temperature matched to prevent stress or shock. Rinse filter media with tank water to preserve bacterial population. Use a test kit to monitor water quality. Ammonia spikes can lead to algae blooms. Ammonia and nitrites should be 0.25ppm or less, nitrates 30ppm or less. If the tank is not "mature" or fully cycled, the excess wastes from fish can feed algae or bacterial overgrowth.
  It may also be diatoms which are harmless and can appear a few months after a tank had cycled. They'll resolve on their own in a month or two. Keep on top of cleaning and water quality.

  

  1Pet Parents found this answer helpful

• Answered By Angel Alvarado, LVT

  Licensed Veterinary Technician

  Published on October 19th, 2017

  This cloudiness is likely due to a bacterial bloom. This can happen if a tank is not properly cycled. Changing the water may make the condition worse. The fish could have been killed by elevated ammonia or nitrite levels. Use a home test kit or submit a water sample for testing. Most pet or fish stores will do this for free or for a nominal fee. If it is a new tank, allow it to properly cycle. This can take 4 or more weeks for the beneficial bacteria to populate the tank and filter. Once ammonia and nitrites are at 0.25 ppm (parts per million) or less and nitrates are at 40ppm or less, you can add fish. Goldfish are cold water fish and do best between 65 F and 72 F. They also need a larger aquarium than most fish. 20 gallons per fish plus an additional 10 gallons for each additional fish is recommended. They produce a larger than normal bio load which can quickly foul water, so a filter rated for at least twice the tank volume is strongly recommended as well.
  

  

  5Pet Parents found this answer helpful