How Long Does It Really Take for Velvet to Kill A Fish?

[mjreefs]

Just would like to start a discussion on the topic. With my fairly recent battle with velvet, I've only suffered a few fish dying from this horrible disease. I was able to save a Powder Blue Tang exhibiting symptoms for 1 week (swimming by the powerhead). We were all told that it kills fast, but the question is, how fast? I'd like to hear what others would have to say, starting from the time symptoms appear until the fish perishes. Also, does fish size matter? My hypothesis is that smaller fish have a smaller time frame for survival than fairly larger fish.

 

[HotRocks]

There are a few factors that come into play. The biggest is type of fish. An acanthurus tang is much more succeptable than a Wrasse due to thickness of mucus layer. They strain of velvet you are dealing with will also play a role. The other huge factor is the overall health and immune system of the fish you are dealing with. Very healthy, well established fish are going to stand a greater chance.

The range of time can be anywhere from a few days all the way up to months of survival without treatment.

Velvet cycles very fast, so the presence of free swimmers increases every 48 hours. A malnourished tang could succumb to the parasite within a few days whereas a healthy Wrasse or goby may be able to tolerate it for months before it's an issue.

 

[mjreefs]

There are a few factors that come into play. The biggest is type of fish. An acanthurus tang is much more succeptable than a Wrasse due to thickness of mucus layer. They strain of velvet you are dealing with will also play a role. The other huge factor is the overall health and immune system of the fish you are dealing with. Very healthy, well established fish are going to stand a greater chance.

The range of time can be anywhere from a few days all the way up to months of survival without treatment.

Velvet cycles very fast, so the presence of free swimmers increases every 48 hours. A malnourished tang could succumb to the parasite within a few days whereas a healthy Wrasse or goby may be able to tolerate it for months before it's an issue.

I see, but sometimes I read posts saying, "If it was velvet, it would've been dead by now" but most of the time, it is really velvet, it's just that the fish's immune systems are still combating it, thus giving the fish a fighting chance. Also, do fish develop resistance (even temporary) to a certain strain of velvet especially healthy, established ones? Of course, we have no way to know how many strains are there infecting the tank, but if we assume that there is only a single strain, aren't they supposed to be able to combat the disease and develop resistance (whether temporary or permanent)?

 

[EmdeReef]

Keep in mind that the infection often starts well before we can see any symptoms. A few parasites attached on the fish initially may not cause issues. So a fish may in fact be infected for days before we spot symptoms and that’s why it’s hard to accurately answer your question.

Once symptoms are visible it would depend on the factors @HotRocks outlined. In addition there are environmental factors such as dilution, infections in a large tank with fewer fish are generally going to be milder increasing the odds of survival.

Lastly there’s the Russian roulette of pathology, e.g.if the infection is too concentrated around the gills the death may occur in hours vs.the body etc.

I’m not familiar with research into velvet immunity but it’s likely safe to guess that a fish could develop an immune response (at least partial) over time - provided it survives.

 

[Paul B]

That is a question that can't be answered. All fish have a degree of immunity and in some cases Velvet won't affect a fish at all, in other cases the immunity will not be strong enough and they fish may succumb after a month or two, but sometimes, the fish lost it's immunity and velvet could kill it in a couple of days.

 

[Frtdrmrose7]

As stated above many factors come into play. A new fish that was shipped will be very stressed and more succeptible where as a healthy fish that is established may be able to fight it off longer. I’ve had Wrasses in QT where one died quickly and the others didn’t. There really isn’t a set time table but Velvet is typically a quick killer I believe because it comes in on new fish who are stressed.

 

[Mattdavid121]

To touch up on this matter, my yellow tang and blue tang have had velvet on and off for about 5-6 months. I have taken every fish out of my tank. Left it barren for 5 months. And when they returned within a few days the white spots covered the fish in mass amounts, fins gills etc. they eat regularly show no signs of panic and fight it off every time. One day I’ll see the blue tang covered in spots then in 48 hours everything is gone.
I have stopped removing them and started using selecon concentrate. I haven’t lost a fish yet. Also, I agree with the wrasse, he’s been in there for a while and has shown no signs of velvet. Same goes for my convict tang and flame.
As far as the yellow and blue tang, the spots come and go.

 

[Rosiefishes]

To touch up on this matter, my yellow tang and blue tang have had velvet on and off for about 5-6 months. I have taken every fish out of my tank. Left it barren for 5 months. And when they returned within a few days the white spots covered the fish in mass amounts, fins gills etc. they eat regularly show no signs of panic and fight it off every time. One day I’ll see the blue tang covered in spots then in 48 hours everything is gone.
I have stopped removing them and started using selecon concentrate. I haven’t lost a fish yet. Also, I agree with the wrasse, he’s been in there for a while and has shown no signs of velvet. Same goes for my convict tang and flame.
As far as the yellow and blue tang, the spots come and go.

Can someone on this thread explain if this means surviving fish are ever able to return to the display tank if they are showing no symptoms after treatment. Or are they forever infected with the parasite. I am battling velvet at the moment and have 2 clowns, a Valentini puffer, a chalk goby and a yellowtail damsel who have survived so far. They are being treated in the main tank as I didn’t have a QT at the time of the outbreak. I was planning to see the course of copper sulphate through in there. I have now purchased another tank which is already cycled as it came from a friend with all the water. I wanted to move them over once treatment was finished but am worried they may just take the velvet with them to another tank. Any advice on what to do would be great.