Re:Now What??

Pete Giwojna

Dear Kris & Seagazer:

The situation Seagazer is describing sounds very much like a copepod bloom, an uncommon problem that sometimes crops up in closed-system aquaria when the population of cyclopoid copepods explodes unchecked. Although the copepods themselves are harmless, when a major copepod bloom occurs the sheer numbers of these tiny crustaceans can physically clog the gills of fishes and result in asphyxia or suffocation. Of course, I would be happy to share my thoughts on this matter with you.

For starters, here’s how I described this condition in the Step-By-Step Book about Seahorses:

"Aquarists unwittingly cause a different sort of problem when they introduce copepods such as Cyclops to the aquarium while feeding live foods. These minute crustaceans reproduce at a fantastic rate (over a year’s time, the descendents from a single female may number over 4 billion) and can quickly transform your aquarium into a copepod soup. When your seahorses try to breathe this copepod-infested water, their gill tufts can become hopelessly clogged by tangled masses of the tiny creatures, resulting in suffocation. As the respiration becomes increasingly labored, the seahorses will signal their distress by panting for breath and going through a series of color changes.

"This problem is easily diagnosed by the cloudy or hazy appearance of the water. It can be treated by running a bedtime filter continuously for several days, while adding three drops of methylene blue per gallon of water. The diatom filter physically removes the copepods, while the methylene blue further reduces their numbers and aides the seahorses breathing. A complete water change is then called for…" [Giwojna, 61-62]

Nowadays, of course, hobbyists are all very conscious of the benefits copepods can provide as a highly nutritious natural food source for seahorses. As a result, seahorse keepers will often take special pains to establish harpacticoid copepods in their tanks or to culture them in great numbers for their seahorse fry, and on rightly so; in the 21st century, we are bombarded with articles extolling the many virtues of ‘pods to the point that few aquarists realize anymore that not all copepods are beneficial.

But that has not always been the case. Not too long ago, the aquarium literature was rife with references regarding "copepod pollution" in the fish tank and warnings about "copepod contamination" of the aquarium. In those days, the scientific journals included papers on topics such as "Should We Love or Hate Cyclops" and "Damage to Fish Fry by Cyclopoid Copepods" by Charles C. Davis (Ohio Journal of Science, vol. 59, pp. 101-102, 1959) and similar studies by the Czechoslovakian investigators Babak (1913) and Oliva and Sladecek ( 1950) describing attacks by Cyclops copepods on Axolotl fry. As an example, Davis points out in his paper that, "There Is clear and incontrovertible proof in the scientific biological literature that some of the species of Cyclops are predators… All Cyclops, whether vegetarian or carnivorous, have biting mouthparts, and in most of them the jaws are adequately powerful to cause significant damage to small fry." Suffice it to say there are countless species of copepods, a number of which are parasitic and a few of which are predatory, and even the harmless varieties can present problems on rare occasions when their numbers get out of control.

For instance, this is what Mildred Bellamy has to say regarding copepods in her famous book Encyclopedia of Seahorses:

"Although nonparasitic themselves, some copepods may still contribute to the death of fishes maintained in close-system aquaria by affecting respiration adversely. This condition is brought about by clogging of the gills or, in the case of the seahorse, the gill tufts, to a point were actual suffocation occurs in the fish involved. Copepods are prolific individuals indeed and, in the closed-system Celeste aquarium particularly, they may reproduce so rapidly as to almost stagger the observer who dips a sampling of water from the aquarium and examines it microscopically.

"In the wild, any freshwater pond will afford millions of [copepod] specimens of the genus Cyclops. The sea contain species of the same genus in such numbers that they, with allied genera, form a large part of the food of many fishes — even some species of whales find in them an abundant food supply. The reproductive powers of Cyclops are so great it has been estimated that the descendents of one female may number 4,500,000,000 individuals in a single year.

"Thus, uncontrolled in the aquarium, it is not difficult to envision how the water, swarming with these minute crustaceans, can become literally a nursery and that the mere circulation of such polluted water over the gill puffs of seahorses can be responsible for depositing thereon life-threatening masses of copepods.

"The gill tufts of seahorses living in water abounding in copepods will be found to contain "mounds" of the small creatures, those underneath voluntarily clinging to or crushed against the tender tuft tissue, with more and more individuals deposited on the initial layers. Then, as additional copepods are drawn into the tufts with the water circulated for the seahorse’s oxygenation, the copepods antennae, tail appendages, leg and body filaments become hopelessly entangled. Unable to move, the copepods continue to pile up until their bodies completely choke the vital area. Suffocation of the involved fish is inevitable.

"In the closed-system aquarium, the first warning of copepod contamination appears as smoke in the water; that is, the aquarium water looks as though it had smoke evenly diffused through it. Progression of this type of pollution causes the water to become smokier and smokier and finally, to assume a clouded yellowish or brownish tinge. Fish maintained in this kind of water often "pant" for breath and frequently go through a series of varied and variable color changes.

"… So much emphasis has been placed on the value of Cyclops as food for young fish that it may be possible their deleterious effect on some larger fishes has been overlooked…

"Although I have proposed that seahorses may become parasitized by way of the food chain and that aquarium water may become copepod-polluted, I want to emphasize here that I’m not recommending the discontinuance of live food. To the contrary, as I’ve stated elsewhere, seahorses require living food and will not long survive if they are deprived of it.

"On numerous occasions when Cyclopoid copepods have become established in my aquarium, I have tried almost everything in the book to reduce their numbers without harming the fish inmates, but I have yet to discover a satisfactory method for getting rid of the so-called innocuous yet devastating pests. In experimental containers, they have survived in water heated to 95°F, or cooled to 44°F. Hardy individuals, although slowed down considerably, have survived in water cooled to 39°F. Although some die, great numbers will live in water without artificial aeration much longer than most species of marine fishes will tolerate the condition. As far as chemicals are concerned, the dosage required for effective eradication usually will kill the fish long before the helpless-looking copepods succumb. A power filter is of slight value. A complete change of the aquarium water is perhaps the most helpful, but this is not a cure. I have tried dipping the fish up and down, literally "bathing" each individual, through several changes of clean saltwater in plastic pails or auxiliary aquaria set up for the purpose, wiping body surfaces gently with a soft wet cloth or sponge, and using wet cotton-tipped Q-sticks around the vents, gill chambers, etc. to rid all areas of accidentally or purposely clinging organisms before returning the fish to their home aquarium, the latter having been cleaned thoroughly and refilled with AIDS, filtered seawater that was free of copepods. Sometimes, within as little as two weeks’ time, incalculable numbers of the odd oar-footed creatures would be seen swarming in the recently cleaned aquarium, quite as thick as before.

"Methylene blue, three drops per gallon of water, does seem to help some. The water clears and the copepods appear reduced in number three or four days after the treatment but this, too, is no cure. The copepod population begins to build up again and unchecked, reaches nearly astronomical proportions in an unbelievably short time." (Bellomy, 181-183; when 86-187).

So that’s what you’re up against when cyclopoid copepods explode in a closed-system aquarium, Seagazer. I should point out, however, that Mildred Bellamy’s book is long outdated and that nowadays we have a number of chemotheraputics that will effectively eliminate a copepod bloom from your aquarium.

Today, my recommended treatment for a bad case of copepod pollution would be to transfer all of the seahorses into clean saltwater in a quarantine tank medicated with a full dose of methylene blue. While the seahorses were being treated in the QT tank, I would then eliminate the cyclopoid copepods from the main tank.

Micron filtration such as that provided by a Diatom filter may help, as recommended in my old step-by-step book, but the filter media will clog frequently and you need to be prepared to recharge the diatom powder frequently until the aquarium clears.

A better option is to treat the aquarium with Parinox, or any other aquarium medication containing Dylox as an active ingredient, after first removing any sensitive invertebrates such as the shrimp or micro-hermit crabs or micro-starfish from your cleanup crew. Formalin will also work to eradicate a copepod bloom, but in that case the trick is to use just enough to formalin to kill off the Cyclops without destroying the beneficial nitrifying bacteria in your biofilter.

I would not swab or otherwise attempt to physically unclog the seahorses delicate tufted gills; the affected seahorses should be able to clear their gills on their own without any assistance providing the aquarist simply prevents them from becoming continually reinfested.

In re-reading your initial post on this, Kris, it strikes me that the scenario you described also closely matches a case of copepod contamination. I now suspect that the initial improvement of the seahorses was due to transferring them to clean seawater that was not infested with cyclopoids and that the subsequent recurrence of the same problem was due to copepods transferred with the seahorses reproducing in large numbers in a hospital tank. The fact that this coincided with a reintroduction of the suspect heater was probably just coincidental; most likely, it simply took a few days for the copepod population to reproduce to problematic numbers in your quarantine tank after the seahorses were transferred there. I may very well have missed the diagnosis on this one, led astray by the coincidental timing, the suggestive knowledge that your test of the heater indicated some stray voltage, the fact that I have observed similar symptoms (swimming agitatedly at the surface accompanied by labored breathing) in seahorses that were receiving a tingle from such voltage, and the fact that it’s been many years since I’ve encountered a bona fide case where a copepod bloom proved harmful.

In any case, now that you’re aware of the problem and know what to do should it ever crop up again, I don’t think you need to have any reservations about stocking your new 75-gallon aquarium with seahorses. Just make sure you install a titanium grounding probe as a precaution and be aware of the potential for a copepod bloom, unlikely as that may be.

I should also point out that you guys mustn’t be overly alarmed by the bloom of copepods your tanks’ recently experienced. Copepods in general are very beneficial and desirable in the aquarium, and potentially dangerous copepods blooms are really exceedingly rare occurrences.

In your case, Kris, the breathing of your seahorses will be the best indication that your copepod bloom has reached potentially harmful proportions. As long as the seahorses are breathing normally, all is well. But if they begin to show signs of huffing, labored breathing, or respiratory distress, then it’s time to eliminate the pesky ‘pods. In that event, here’s some information regarding the best way to administer methylene blue:

Commonly known as "meth blue" or simply "blue," this is a wonderful medication for reversing the toxic effects of ammonia and nitrite poisoning. Methylene blue transports oxygen and aids breathing. It facilitates oxygen transport, helping fish breathe more easily by converting methemoglobin to hemoglobin — the normal oxygen carrying component of fish blood, thus allowing more oxygen to be carried through the bloodstream. This makes it very useful for treating gill infections, low oxygen levels, or anytime your seahorses are breathing rapidly and experiencing respiratory distress. It is the drug of choice for treating hypoxic emergencies of any kind with your fish. However, methylene blue will destroy nitrifying bacteria so it should only be used in a hospital tank (if used in an established aquarium, it will impair the biological filtration and the tank may need to be cycled all over again).

If you can obtain the Kordon brand of Methylene Blue (available at most well-stocked local fish stores), their suggested treatment protocol for nitrite poisoning is as follows, and would work equally well in eating the breeding of seahorses with copepod-clogged gills:

As an aid in reversal of nitrite (NO2-) or cyanide (CN-) poisoning of marine and freshwater aquarium fishes:
(a) Remove carbon filter and continue to operate with mechanical filter media throughout the treatment period.
(b) Add 1 teaspoon of 2.303% Methylene Blue per 10 gallons of water. This produces a concentration of 3 ppm. Continue the treatment for 3 to 5 days.
(c) Make a water change as noted and replace the filter carbon at the conclusion of the treatment.

See the following link for more information on treating with Kordon’s Methylene Blue:
Click here: KPD-28 Methylene Blue

Best of luck with your seahorses, Kris and Seagazer!

Pete Giwojna

Post edited by: Pete Giwojna, at: 2006/01/24 16:12

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