I'm sorry sir, but with all due respect... I strongly disagree with your clarification. There's is absolutely no way for you to say 100% sure that this fish was only suffering with Ich. I was there and watched the fish. You were not. There is no way for you to know. Velvet will not "ONLY" present with tachypnea. Velvet has many other stages and signs depending on what part of the life cycle it's currently in. Initially, some fish show very little or ZERO visual signs. Velvet does not ALWAYS kill a fish like you mentioned above. Please show me any documentation for the claims you made. The burden of proof is on you since you made the assertions. Best of luck.
Hello,
Respiration rates are a key diagnostic in this case. I've studied rates in aquarium fish for 30+ years. The fish in your video was breathing about 80 BPM, just slightly elevated. With Amyloodinium, severe enough to cause body lesions, the respiration rate would be 150+ BPM. Here is my reference: Hemdal 2019. Breathe Easy – Using Fish Respiration Rates to Determine Relative Stress Levels in Fish. Coral 16(4):104-111
Please see Noga's Fish Disease P. 146 He describes this as primarily a gill disease, with skin lesions being secondary. He then says about skin spots, "...however, this is not a common finding, and fish often die without obvious gross skin lesions." He also says definitive diagnosis can only be made by gill biopsy.
In the landmark paper involving peroxide treatment of Pacific threadfin, Montgomery et-al says, "The primary infection site appears to be in the gills..."
Goemans and Ichinotsubo: "One of the first signs of this disease may be rapid breathing..."
Finally, here is an excerpt from my Aquarium Fish Disease book:
Amyloodinium (a.k.a. marine velvet disease)
Cause
Commonly known as “marine velvet” in hobby parlance, Amyloodinium is caused by a dinoflagellate protozoan that can produce severe epidemics in aquariums. Furthermore, it can infect fishes that are normally more resistant to other marine protozoan diseases (e.g., Cryptocaryon), such as sharks, rays, and eels.
Symptoms
The life cycle of Amyloodinium is very similar to that of Cryptocaryon, as are the possible treatments available, but it has less distinctive early symptoms and can cause fish mortalities much sooner than other protozoan infections—sometimes within 12 hours of the onset of obvious symptoms. This disease begins as an infection of the fish’s gills, and only in advanced cases does it spread to the skin, giving it a “velvety” look. Symptoms include rapid breathing and hovering in the current from pumps.
Beginning aquarists often miss the first symptoms and commonly report, “All my fish suddenly died, but the invertebrates are all fine.” Since invertebrates are typically more sensitive to water-quality issues than fish are, the fact that the fish suddenly died but the invertebrates were unharmed means that water-quality problems can be ruled out. That leaves a fish disease, and Amyloodinium can often be diagnosed without even needing to perform a necropsy on the fish due to the rapidity of the fish loss!
Diagnosis
The key to early diagnosis of Amyloodinium is to monitor the fish’s gill health by taking regular fish respiration rates. This is a simple matter of counting the number of gill beats in one minute for a representative fish in the aquarium and then rechecking the respiration rate every few days to watch for any elevation in that rate.
Newly acquired fish that are not being treated prophylactically should have their respiration rate checked daily, as these fish are the ones at greatest risk of developing this disease. The actual respiration rate is not that important, it is a rise in the rate that must be monitored for.
Different species of fish will respire at different rates. Smaller fish breathe faster than large ones, and fish in warmer water will respire faster as well. Typically, tropical fish will respire between 60 and 120 gill beats per minute. If you can’t view the fish for a full minute, you can try counting for 15 seconds and multiplying the result by four.
Knowing your fish’s normal baseline respiration rate is vital; any rise in that rate above 30% (and not attributable to something else, such as the fish being chased by a tankmate) should be viewed as a possible symptom of this disease.
Treatment
Treatments for Amyloodinium cannot be performed with invertebrates present, yet the entire tank usually needs to be treated in order to eradicate it. Copper sulfate at 0.20 ppm for 14 days is one often-used cure. Chloroquine at 8 to 15 ppm as a 30-day static bath is another treatment that has been used with good success.
Performing a five-minute freshwater dip can buy some time in order to develop a full treatment. Hydrogen peroxide dips and moving the fish to a sterile aquarium has been used in aquaculture. Lowering the tank’s temperature is rarely effective. Likewise, hyposalinity treatments (sometimes recommended for Cryptocaryon treatments) will not work for Amyloodinium.
Jay
