Marine Aquarium Problem? Don’t Panic!

Don't panic when a problem arises in your aquarium. Take a moment to understand the situation rather than hastily react.

Don’t panic when a problem arises in your aquarium. Take a moment to understand the situation rather than hastily react.

Henry Wadsworth Longfellow famously wrote, “Into each life some rain must fall.”

For marine aquarium hobbyists, that “rain” often comes in the form of a troublesome algae outbreak, the appearance of an uninvited pest, out-of-whack water parameters, sick specimens, livestock compatibility or behavioral problems, or one of many other potential issues. Simply stated, if you’re involved in the aquarium hobby for any length of time, it’s not a question of if you’ll experience a frustrating problem, but when.

When something does go awry, it’s perfectly natural for the hobbyist to want the problem resolved as soon as possible so tranquility can be restored and enjoyment resumed. But it’s important to keep in mind that many common marine aquarium problems are going to take time to remedy and that overreacting in an effort to quash the problem quickly often just makes matters worse.

That’s not to say that an urgent response is never appropriate. Indeed, some aquarium problems or symptoms warrant immediate intervention. Among them:

  • Detecting ammonia or nitrite in the water
  • Specimens dying
  • A major compatibility issue between specimens (e.g., unabated squabbling)
  • Life-support-equipment failure (e.g., the heater or filter)
  • Any other issue or malfunction that puts your livestock—or your safety—in imminent jeopardy

Most other problems should be considered cause for a course correction, not a reason to panic and resort to drastic measures. Here’s why:

Gradual problems require gradual solutions

Few aquarium problems develop overnight. Most of them build up very gradually and are a result of benign neglect. Algae outbreaks are a prime example of this. You get a little lax with maintenance, space out those water changes just a bit too far, feed with a slightly heavy hand, and eventually you have an elevated level of dissolved nutrients that fuels an algae bloom.

Once the algae gets established, it can be very stubborn to eradicate. Reversing the process requires you to adjust many aspects of husbandry and is sort of like turning an aircraft carrier around. It can’t happen on a dime.

Sudden changes can be stressful

Problems related to water parameters, such as the specific gravity, temperature, calcium/alkalinity, or pH of the water drifting away from the desired value, should be corrected very slowly and incrementally, as sudden changes in these values be can be stressful, or even deadly, to coral reef organisms.

Extreme measures usually treat symptoms

Taking drastic measures may seem to help a troublesome situation initially, but more often than not, it will succeed only in temporarily eliminating the symptom of a problem—not the underlying problem itself.

Take cyanobacteria (a.k.a. blue-green algae or BGA) for example. When contending with a smothering coat of this gunk in their tanks, some hobbyists resort to treating the system with an antibiotic. In the short term, dosing antibiotics may kill the existing growths of BGA, and all will seem well, but it will do nothing to address the underlying problem of excessive dissolved nutrients and inadequate water circulation. Thus, the symptom soon returns. (Not to mention, the antibiotic might also kill the beneficial nitrifying bacteria in the system, thereby wiping out the system’s biological filter.)

Some problems aren’t necessarily problems at all

Most of us have been conditioned to view certain organisms as unwelcome or even dangerous in marine aquariums—even though they’re a natural part of the ecosystem on and around coral reefs.

Bristleworms, for example, are often viewed as nasty, stinging, coral-eating pests that need to be eradicated with extreme prejudice. Indeed, some species, such as the notorious bearded fireworm (Hermodice carunculata), do predate on corals and other sessile invertebrates and can deliver a painful sting with their calcareous bristles. However, the vast majority of these polychaete worms are harmless and actually beneficial consumers of detritus.

If you come across one (or more) in your aquarium, you don’t necessarily need to do anything about it unless you can confirm it’s one of the nasties. In any case, I’d still recommend wearing heavy-duty protective gloves when working in a tank containing bristleworms, however.

Some problems resolve on their own

Some perceived problems have a way of working themselves out naturally if hobbyists will just leave well enough alone. For instance, a newly introduced fish staying hidden for several days to weeks can be a major source of anxiety to hobbyists, who worry because they can’t determine whether the specimen is healthy and uninjured—or even still in the tank—and they can’t verify that it’s getting anything to eat. The temptation in this situation is to disassemble the rockwork and eliminate the fish’s hiding place, which only serves to stress the specimen further.

This behavior is perfectly normal and almost always resolves once the fish has had a chance to get settled in and accustomed to its new home and tankmates (assuming it’s not getting bullied). So stay calm, carry on with proper maintenance and husbandry, and your shy fish should soon come out of hiding.

Small, routine adjustments keep problems at bay

Because most aquarium problems develop gradually over time, observant hobbyists can often detect them early on if they make the effort to test their water regularly and keep a close eye on the behavior and health of their livestock. And, generally speaking, the earlier problems are caught, the easier they are to correct.

Photo Credit: skippyjon


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About Jeff Kurtz

Jeff Kurtz is the Co-founder/Editor of Saltwater Smarts, former Senior Consulting Editor for Tropical Fish Hobbyist Magazine, and the aquarist formerly known as “The Salt Creep.” He has been an aquarium hobbyist for over 30 years and is an avid scuba diver.


  1. Enjoy all your articles. Keep ’em coming!

    • Chris Aldrich says

      Thank you, Tony! We’re glad you’re enjoying them.

      We sure will keep them coming, no worries there. 🙂

  2. Miguel Peguero says

    Great article. But what about when dealing with dinoflagellates?
    I’m losing this battle and am afraid I’ll loose everything. Been thinking of relocation my fish and coral temporarily. Emptying the tank and sump of all water. Scrubbing all rock of Dino sifting the sand. Adding new ro/di water and new salt. And adding bacteria. Closing of all light from entering tank for a few days. Then re introduce fish.
    I know it’s drastic but I’m at my witts end.

    • Thanks for your kind comment, Miguel, and sorry to hear about your frustrating battle with dinoflagellates. Ironically, I just recently happened upon an intriguing article on dinoflagellates written by Randy Holmes-Farley, in which he explores the concept of treating this problem by elevating pH. If you haven’t read it yet, you might want to look it over before doing anything too drastic with your system. Below is a link to the article. I think you’ll find it worthwhile reading.

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