Dosing Praziquantel (PZQ)

[xzt]

Can Moorish idols be treated with praziquantel? Yesterday, I dissolved 2.5 ppm of praziquantel in 30 ml of ethanol and added it to my fish tank. The next day, all four Moorish idols died, and the water turned white and cloudy. I had an oxygen pump running, but why did it still cause the death of the organisms?

 

[winxp_man]

what’s the tank size?

So you cut .01 gr of prazi with 30ml ethanol? That crazy if you ask me. I dose .50 gr of prazi with 2ml of everclear for a 50 gal QT.

Did you dose in a QT or DT?

 

[Jay Hemdal Verified Community Expert]

Can Moorish idols be treated with praziquantel? Yesterday, I dissolved 2.5 ppm of praziquantel in 30 ml of ethanol and added it to my fish tank. The next day, all four Moorish idols died, and the water turned white and cloudy. I had an oxygen pump running, but why did it still cause the death of the organisms?

Sorry to hear that!

That sounds like it is from the large amount of ethanol being decomposed by bacteria. I never use ethanol any longer as a solvent, it is too risky. If you do use it, you need to use the very smallest amount possible, to basically just make a slurry.

As I say in the article, I prefer to express the PZQ into the tank through a fine mesh net.

 

[xzt]

Sorry to hear that!

That sounds like it is from the large amount of ethanol being decomposed by bacteria. I never use ethanol any longer as a solvent, it is too risky. If you do use it, you need to use the very smallest amount possible, to basically just make a slurry.

As I say in the article, I prefer to express the PZQ into the tank through a fine mesh net.

So, the drug praziquantel is actually safe for Moorish idols, but ethanol may cause some other side effects, right?

 

[winxp_man]

So, the drug praziquantel is actually safe for Moorish idols, but ethanol may cause some other side effects, right?

Not necessarily. You just dosed too much which caused such a bacteria bloom it killed the fish. No oxygen.

It’s why in my posted I stated that for a 50 gal tank I use 2ml. Just enough to mix the powder.

 

[Jay Hemdal Verified Community Expert]

So, the drug praziquantel is actually safe for Moorish idols, but ethanol may cause some other side effects, right?

Yes, I use pure PZQ powder on idols all the time with no issues, it was the large amount of ethanol that you used that caused a bacterial bloom. That in turn took up oxygen from the water, and idols don't tolerate low oxygen levels. In some tanks, there is not sufficient aeration to use ANY solvent at all, so I always avoid it.

 

[xzt]

Yes, I use pure PZQ powder on idols all the time with no issues, it was the large amount of ethanol that you used that caused a bacterial bloom. That in turn took up oxygen from the water, and idols don't tolerate low oxygen levels. In some tanks, there is not sufficient aeration to use ANY solvent at all, so I always avoid it.

My system even contains some higher algae, which might also consume oxygen at night. I have used ethanol in other tanks before, which similarly caused the water to become cloudy. However, at that time, the water quality parameters and dissolved oxygen levels I tested were within the normal range, and the fish showed no signs of abnormality. After a few days, the aquarium water cleared up on its own. That's why I didn't monitor the dissolved oxygen in the water this time.

 

[xzt]

Not necessarily. You just dosed too much which caused such a bacteria bloom it killed the fish. No oxygen.

It’s why in my posted I stated that for a 50 gal tank I use 2ml. Just enough to mix the powder.

Because I found through research that the solubility of praziquantel in ethanol is only 10%. Therefore, I used 30ml of anhydrous ethanol to dissolve 3g of praziquantel in 300 gallons of water. But actually, using a smaller amount of ethanol to make a suspension of praziquantel is equally effective, right?

 

[winxp_man]

Because I found through research that the solubility of praziquantel in ethanol is only 10%. Therefore, I used 30ml of anhydrous ethanol to dissolve 3g of praziquantel in 300 gallons of water. But actually, using a smaller amount of ethanol to make a suspension of praziquantel is equally effective, right?

For me it was fish I knew had flukes. Saw them flash, and scratch. And they were in copper only till the prazi dose. And it worked just fine. So I had about 2ml of everclear alcohol, with .5 gr of prazi for a 50 gal system. QT so I know the exact amount of water I have in it. I used 5gal buckets to measure to the exact amount.

 

[Jay Hemdal Verified Community Expert]

My system even contains some higher algae, which might also consume oxygen at night. I have used ethanol in other tanks before, which similarly caused the water to become cloudy. However, at that time, the water quality parameters and dissolved oxygen levels I tested were within the normal range, and the fish showed no signs of abnormality. After a few days, the aquarium water cleared up on its own. That's why I didn't monitor the dissolved oxygen in the water this time.

Yes - reverse phase photosynthesis at night, combined with the activity of the heterotrophic bacteria consuming the ethanol can crash the dissolved oxygen in a tank. Getting a good read on dissolved oxygen is tough, even DO meters are prone to inaccuracy, so it is really difficult to track this issue in real time.

 

[Jay Hemdal Verified Community Expert]

Because I found through research that the solubility of praziquantel in ethanol is only 10%. Therefore, I used 30ml of anhydrous ethanol to dissolve 3g of praziquantel in 300 gallons of water. But actually, using a smaller amount of ethanol to make a suspension of praziquantel is equally effective, right?

Yes, solubility of PZQ is fairly low in ethanol, but actually, it is just used as a dispersant, you mix it into a slurry and then add it to the tank, because once it hits the water, it immediately comes out of solution anyway. You can see that when using Prazipro (that uses a glycol solvent). The solution is clear, but when added to the tank, it forms a light haze - those are tiny particles of PZQ coming out of solution. It still works as tiny particles....that's why pushing it through a fine mesh net still works. I've always wondered if it is just the tiny particles of PZQ hitting the flukes that causes them to drop off?

 

[xzt]

Yes, solubility of PZQ is fairly low in ethanol, but actually, it is just used as a dispersant, you mix it into a slurry and then add it to the tank, because once it hits the water, it immediately comes out of solution anyway. You can see that when using Prazipro (that uses a glycol solvent). The solution is clear, but when added to the tank, it forms a light haze - those are tiny particles of PZQ coming out of solution. It still works as tiny particles....that's why pushing it through a fine mesh net still works. I've always wondered if it is just the tiny particles of PZQ hitting the flukes that causes them to drop off?

Thank you for your reply. I am no longer being lazy; instead, I am slowly rubbing praziquantel into the fish tank using pantyhose.

 

[kboogie]

I want someone to check my logic. If I have a 5 gallon QT, my does would be as follows:

3.8l per gallon, so 5 x 3.8 =19l

2.5mg/l of pure Prazi powder, so 2.5 x 19 = 47.5mg
So I need to use 47.5mg of pure Prazi Powder?

 

[Jay Hemdal Verified Community Expert]

I want someone to check my logic. If I have a 5 gallon QT, my does would be as follows:

3.8l per gallon, so 5 x 3.8 =19l

2.5mg/l of pure Prazi powder, so 2.5 x 19 = 47.5mg
So I need to use 47.5mg of pure Prazi Powder?

Yes - that's correct, however, your 5 gallon tank may only hold 4.5 gallons of actual water, and your 2.5 mg/l dose is a bit higher than the normal 2.2 mg/l dose. I came up with 38 mg. You can buy a digital gram scale on Amazon for about $16.

 

[kboogie]

I want someone to check my logic. If I have a 5 gallon QT, my does would be as follows:

3.8l per gallon, so 5 x 3.8 =19l

2.5mg/l of pure Prazi powder, so 2.5 x 19 = 47.5mg
So I need to use 47.5mg of pure Prazi Powder?

Yes - that's correct, however, your 5 gallon tank may only hold 4.5 gallons of actual water, and your 2.5 mg/l dose is a bit higher than the normal 2.2 mg/l dose. I came up with 38 mg. You can buy a digital gram scale on Amazon for about $16.

I realized I was grossly under dosing my original QT.

 

[kboogie]

Any concerns with Anthias and Prazi? I have four large Squareback Anthias (1M3F) in my other QT that are eating well and I’m at the stage where I’m ready for Prazi.

 

[Jay Hemdal Verified Community Expert]

Any concerns with Anthias and Prazi? I have four large Squareback Anthias (1M3F) in my other QT that are eating well and I’m at the stage where I’m ready for Prazi.

No specific issues with anthias, just ensure good aeration if using orazipro

 

[kboogie]

After looking at my scale, I actually wasn't underdosing in the past.

 

[Bobobble]

No, i didnt see any eggs at all. Just the flukes that were actually attached. Hes scratching the sand again today - i just got the prazipro picked up yesterday and getting the QT water mixed up now. So i plan to dip again before moving to the QT tank. (Along with my diamond goby and scooter blenny)
I used the orange bucket since i didnt have black and saw nothing on the bottom.

Side note - i know airation is needed. Can i just run a sponge filter in place of a HOB? I also have a bubbler i can use too.

Using a 29 gallon tank with about 25 gallons of water in it.

Sponge filters work to supply aeration.

I’ve read online it can be a issue running aeration on a DT with bunch of coral. Is this true? If it is would one the same thing running the aeration on the sump ?

 

[Jay Hemdal Verified Community Expert]

I’ve read online it can be a issue running aeration on a DT with bunch of coral. Is this true? If it is would one the same thing running the aeration on the sump ?

I'm not sure why people would say that. Physical bubbles hitting the corals isn't good, and really heavy aeration can drive off some carbon dioxide that the coral's zooxanthellae need, but fish die pretty quickly in low oxygen environments, so during a treatment, good aeration is important.

A strong protein skimmer in a sump may be enough aeration if using plain prazi powder, but I always add an air stone in the main tank when treating with Prazipro. That product has an extra solvent that bacteria consume, using up oxygen.