Saltwater Aquarium Problems: Answers & Help

For emergencies, large or small. If you’re having a serious issue with your saltwater aquarium, this page can help. It provides information to troubleshoot some of the most common problems seen by aquarists. Can’t find the answers you need? Call the Instant Ocean® customer service hotline at 1-800-822-1100, 8:30 a.m. to 4:30 p.m. Eastern Time, Monday through Friday.  If you're calling from Canada, please dial 1-440-255-1997.

Instant Ocean Emergency Room

Keeping a marine aquarium lets you create and enjoy a beautiful display of the marine environment. It can be rewarding, relaxing, a place of learning, and from time to time, a challenge. We at Instant Ocean feel marine hobbyists should look to many resources to help keep their pets happy and healthy.

Under critical conditions, you will want to follow some general recommendations to stabilize a problematic situation and provide time to gain more information. We’ve listed these guidelines below. The first step is working with your local respected pet retailer.


  • First identify the situation: Are the fish respiring quickly (gill operculum moving up and down)? Is the water cloudy? Are the fish scratching? Has their behavior changed? Are they eating? Are their fins clamped? Are your invertebrates (sea anemone, corals, etc.) pulled in or withdrawn? 
  • Do a partial water change, 20 to 50 percent.  Make sure your tap water is conditioned, the temperature is matched with your aquarium, and you are using a high quality sea salt. 
  • Check the operations of your aquarium: Is the filter working properly? Is the temperature stable? Is the salinity correct? Is there a film on the water surface and could a contaminant have entered the system (like a cleaning solution)? 
  • Document your aquarium conditions and prepare to seek more information. Use a clean zipper-lock bag to collect a water sample before and after the water change (4 to 6 oz and remove all air before sealing). Try to take a picture of your sick pet to take to your retailer; digital cameras are great. And lastly, use the checklist below to fill out and take to your retailer or other trusted expert. 
  • Ask your retailer about LIFEGUARD®. It treats a broad range of marine fish diseases: bacterial, fungal, viral and parasitic. You can find LIFEGUARD® in leading pet retail stores or in our online catalog.


  1. Observed situation
  2. Tank size
  3. Known water quality
    • Temperature
    • Salinity
    • pH 
    • Ammonia
    • Nitrite
    • Nitrate 
    • Alkalinity 
    • Types of fish and how many 
    • Food being fed, how much and how often
    • Water change history 
    • Filtration method, skimmer, use of carbon or other media
    • Types of products recently added (like trace elements) 
    • Other recent changes