The Ich Test, or My Experience With Salt Cure vs Malachite Green

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Monday, March 11th: Determined that the fish that I had received a little over a week ago were developing ich, probably due to transport stress and some accidental chilling after arrival. Decided to give the popular salt cure a try, although I have had good success with malachite green in the past. Raised the temperature to 84 degrees F, and added a mixture of sodium chloride and magnesium sulfate at the rate of 1 teaspoon per gallon. There are four species of fish in this tank: 6 Labeotropheus (L), 6 Pseudotropheus (P), 6 Pundamilia (H), and 3 Syndontis (S). At this point two H have spots visible on the upper body, and one L is shimmying. All 18 mid-water fish are scraping on rocks and gravel occasionally.

Tuesday, March 12th: Spots increasing on H, another L gone to shimmying.

Wednesday, March 13th: All H have spots, the two worst have spots on both upper and lower body. One L has obvious large spot between eyes, 4 L shimmying, and all L have spots visible on fins. P scraping almost constantly, rocks and gravel.

Thursday, March 14th: All mid-water fish have lost interest in food and are scraping constantly except for L which are all shimmying inside caves. All H have spots top and bottom. Two worst are shimmying. The large spot on head of one L is spreading. I aborted the attempt to prove salt treatment right or wrong at their expense, and began adding 0.75% malachite green at the rate of 15 drops per 60 gallons, morning and evening. This is expected to control the ich by the end of three days, from my past experience.

Friday, March 15th: Spots appear not to be increasing. Large spot on head of L has flattened out. All 6 P and 4 of the H are eating. 3 L have stopped shimmying.

Saturday, March 16th: Spots disappearing. All fish eating. Large spot on head of L now just faint mark. All P & H still scraping rocks and gravel, but not frantic. Displays of coloration have resumed.

Sunday, March 17th: All L have stopped shimmying. Large spot is completely gone from head of L. All but 2 worst H are completely free of spots. 2 worst H have only a few spots. Only casual scraping by P & H, and only on rocks. All fish eating well, including all 3 S. Stopped malachite green addition after morning dose.

Monday, March 18th: All visible spots gone. All fish swimming and eating normally. Very occasionally an H will scrape a plant or rock, but none are scraping the gravel.

Conclusion: Malachite green cured the ich in three days, as has been my past experience. Salt alone did not cure the ich in three days. It cannot be determined whether or not the salt would have worked by the seventh day without the malachite green. however past experience says that the malachite green would have worked in three days without the salt. It remains to be seen whether the normally required repeated treatment of malachite green will be required in the presence of the salt. This repeat malachite green treatment is normally given to kill the ich organisms that were encysted in the gravel during the previous treatment, at an interval which allows the encysted organism to emerge but not to become established on the fish. I have not yet decided whether to risk my fish on a salt-only control of this second stage. (I eventually went with the medication.)

Perceived shortcomings of malachite green versus my experience:

1. Kills plants. I have not found this to be so, but I don't have a wide variety of plants so there may be some that are more copper-sensitive.
2. Destroys biological filtration. I have not found this to be so. My recently treated tank still has unmeasureable levels of ammonia and nitrite.
3. Dyes silicone cement green. I had to actually look for this effect. Yes, the silicone cement on my tanks which have ever been treated with malachite green are a very pale shade of blue-green, pretty much the same color as the edge of the glass but in a paler shade. I'm not sure that, compared to the original color, it is any less attractive. I find the algae growing on some of the cement to be far less attractive. Ditto on the plastic tubing. If the plastic in a tank has turned a brilliant shade of green than my guess is that way too much malachite green was added.
4. Kills the patients, or any smooth-skinned fish in the tank. This hasn't happened for me.
5. Kills invertebrates. I wouldn't even try this treatment with valuable invertebrates. In my case all I had to lose were a few pond snails who had hitched their way in on some plants. I do not know whether to brag or to complain about the fact that said snails appear to be alive and well.
6. Is removed by carbon in the filter before it can work. Yes, it would be. Remove your carbon before adding the malachite green, otherwise you will waste both the carbon and the dye.
7. Costs money to buy. Yes, nothing much can be done about that. I did once make a batch of malachite green, to dye a wool hat for someone, but the chemicals came from the laboratory stock room and would have cost money had I bought them myself. The stuff has an indefinite shelf life, unlike antibiotics, so you can buy a large bottle at a better price and keep it for years.