Ich Myth vs. Velvet

[kveeti]

Re: Velvet (Oodinium pillularis) I am curious about this disease (more why later). All I knew previously about it was what I’d read in passing about how it ‘looks’ on a fish and also that if you read treatments on medicines, velvet is usually listed with ich.

I also know it is a myth about ich always being present in an aquarium, after having read such excellent info as at The Skeptical Aquarist and from Daveedka’s article here and following many myth threads over the last couple years.

The reason I am curious: I heard an excellent presentation on killifish, but for all the genera except Aphyosemion, it was recommended to add 1 tsp non-iodized salt per gallon to their water because they are susceptible to velvet which is always present. My first thought was the non-iodized was unnecessary, it could have just stated salt. So, then I was wondering if this was just another “always present” myth with another disease. If the fish is especially susceptible, then perhaps treating any newcomers with salt in quarantine could be reasonable, but certainly not all the time. However, I've never kept killifish.

I’ve just looked up the lifecycle of velvet and it seems to be a similar Protazoa infection to that of ich, i.e. needs host, cyst, free swimming. Therefore, if you treat velvet for long enough to ensure it is eradicated, then it’s just that, eradicated, right?

 

[sardesign]

I'm not an expert on either disease but logic would lead me to believe (after reading Dave's article and my other research) that no parasites are "always" around. From what I've read, they can hide out for quite a while but I think that may be another myth. Maybe Dave will stop in and clear that up for you.

 

[Sully]

Velvet is a parasite. Like ich it can be eradicated in aquaria.

The common myth concerning the permanent presence is because it is often treated too briefly. The paracide utilized reduces the parasitic load in the tank to the point that physical, visible symptons vanish. Unfortunately that does not mean that the parasite is gone.

Many fish, especially the more mature specimens are able to then mount an effective immune response that holds the parasite at bay. Then when introducing naive fish into the environment the parasite "magically and mysteriously" reappears.

Or, the fish that are introduced, while not being visibly infected, do carry the parasite into the tank. The result then being that someone, somehow guesses, the parasite was present to begin with.

Or maybe, someone believes in the theory of spontaneous generation. And, we are at the mercy of some mysterious natural phenomenon that has been scientifically disproved centuries ago.

As to salt, please do not get me started. I can, and have, written incredibly long posts discussing the purpose and presence of salt in aquaria. The value of salt, in my mind, being an even bigger "myth" than the unbeatable parasites myths you brought up. Salt, like any other treatment in a tank has a role in disease resolution. The continued presence of salt, however, defeats the value of salt in that role. Like other chemical compounds bacteria and parasites will mutate to protect themselves against salt. In turn requiring an escalation of salinity of your water in your tank.

The most effective treatment for fish, as a preventative measure, is the practice of large volume, regularly schedules water changes. Accompanied with gravel vacs and filter cleaning. Those steps will reduce bacterial and parasitic loads while also keeping Dissolved Organic Compounds under control.

The one thing I have learned about fish since I began well over 30 years ago is that there is no replacement for a constant supply of freshwater. The second thing I have learned is that it is pointless to use salt as a "standrd" part of the tank maintenance regime.

Salt does have some role, in some disease treatment therapies. It has no role as a regular additive in your tank.

 

[daveedka]

Agreed with sully (and more than a bit curious about the username)

I would add one key difference between ich and velvet. Velvet has the ability to photosynthesize, and therefore can survive much longer periods without a fish for a host. This is only a key difference if waiting out an infected tank before adding more fish. In any case when treating velvet blackouts do help. If there are no fish in the tank, blackouts and time will kill off all of the parasites. With fish in the tank, velvet requires meds but blackouts are a big help during treatment.

I have not actually treated for velvet at any time since I actually knew anything about it. I did do extensive research because I thought it was the cause of a problem I had at one point. From everything scientific I have been able to dredge up the Skepticle aquarists information on velvet is as accurate as it can be.
Sounds like everyone here is on the right track.
Dave

 

[sardesign]

Dave,

Not that I have this problem right now... but what kind of meds do you treat velvet with (in your opinion)? I'm assuming you cannot use salt

 

[daveedka]

If it were to arise, I'd use formalin and malechite mixture. From what I've read, that is the only surefire treatment feasable. I know there are meds available with these two active ingredients, but do not know by brand name which meds have both. copper will of course kill it, but I will never use copper for any reason. I'd also black out any tank I was treating velvet in. Even when attached to a host velvet uses light, and a blackout will help immensely with the battle.Some folks claim salt alone will kill it, but the skepticle aquarists and a few other places i've searched do not consider salt a surefire treatment. Salt is said to be helpful, because velvet does not like salt but not as sure as salt is for killing ich.
If I was working with ultra sensative fish I might try salt, blackout and half dose meds all together, as this is usually less stressful than full dose meds alone.
Either way once velvet breaks out, quick action is necessary. Everything I've read says it moves fast once it gains a foothold in the tank so to speak. With that in mind, the higher risk factor is inaequate treatment so I'd probably go full dose meds right away unless dealing with my pictus cats. With sensative fish you run into a catch 22 of inadequate treatment/ fish can't handle adequate treatment. I really dread the thought of sensative fish with velvet.
Dave

 

[kveeti]

Thank you. It's what I thought but I just wanted to be sure, especially since the speaker was very knowledgeable about the fish themselves. Unfortunately, I didn't get any killifish at the auction afterward, they were bidding rather high... as always happens after a speaker, I guess. Last month, it was plants and the plants went pretty high. They sounded like great fish to try, though.