Pest mosquitos breeding in my tank

[aquaprawn]

I have freshwater gnats breeding in my tank. They look a lot like mosquitoes and the larvae is constantly seen wriggling in my tank. When I open the top lid, I constantly many adults fly out.

Manual removal of the adults or larvae is no use as it keeps coming back.

 

This is happening in my PRL breeding tank which is semi planted. Its a 75 liter. There are many shrimp babies.

If I add a handful of Mosquito Rasboras (Boraras Brigittae), will this solve the problem and will they also snack on the shrimp babies?

 

How do I solve this pest problem?

 

Thanks.

 

[Shrimple minded]

 

Hi aquaprawn.

 

I too have battled this creature, and I am the victor.  Agreed on manual removal..........could never get ahead.  I considered rasboras but eventually settled on Hockeystick Pencilfish (Nannostomus eques).  The awesome thing about this fish is that they spend all of their time hanging out just below the surface of the water looking for anything to eat off the top of the water.  Upon introduction, they hammered the flies on the surface and I saw total removal probably in 2-3 days.  The flies never returned, and I kept the pencilfish in my 40B mixed tank for probably 1.5 years with no noted incidents.  I recently transferred these fish from card parameters to neo parameters and they did just fine.  They don't have incredible coloration, but with their tiny mouths and spending 100% of their time guarding your surface, I consider them to be near-perfect for shrimpers.

 

I sourced my hockeysticks via Rachel O'Leary @ msjinkzd.com.  As many others, I rate her highly, her communication was awesome and she answered all kinds of questions.

 

Below is a post from my previous adventures with other fish ideas as well.  Search this forum for "green flies" and you should return a few other results.

 

Good luck and feel free to hit me up here or via PM if you have additional questions.  SM

 

[aquaprawn]

Thank you SM. I read every word of your adventure with interest and will look for Hockeystick Pencilfish. I've never heard of the fish, so thanks for introducing it to me. I will try to look for them in the LFS but I don't think I can purchase them online as I'm on the other side of the globe

 

I did manage to find a different variety of Pencilfish though.

https://www.lelong.com.my/pencil-fish-aquarium-fish-aquacult-181964387-2018-08-Sale-P.htm

 

I think this is N. unifasciatus. I've definitely seen this in LFS, but I think this variety won't do as this one likes the mid to lower part of the aquarium.

The variety you mentioned was N. eques. I'll need to look for that.

 

Can I ask is the Hockeystick Pencilfish a very small fish? About 30 or 35mm?

 

I do readily have Chilli Rasboras though as they're in my other 3 footer tank.

 

[Shrimple minded]

Yes, exactly in this size range (3-4 cm)

 

If it were me I would likely try the rasboras you already have and just keep an eye on them.  I don't think any fish is 100% baby shrimp safe, but often times when this question comes up on forums rasboras come up as the most-likely candidates.  I would think that once they figure out there are flies on the surface they'll have a little feeding-fest and knock them out in days, after which time you could transfer them back out.  I'm hoping your experience is like mine in that once the flies were eradicated, they never came back.  This occurred on my first tank immediately after set up when I moved shrimp to my basement area, and hasn't occurred on any of my other 7 shrimp tanks now on the same rack.  

 

If you do try the rasboras, please let us know how it works out.  This problem seems to come up infrequently but I know I hated it, and was willing to consider all options to fix the issue.

[aquaprawn]

On 04/05/2017 at 11:36 AM, Shrimple minded said:

Yes, exactly in this size range (3-4 cm)

 

If it were me I would likely try the rasboras you already have and just keep an eye on them.  I don't think any fish is 100% baby shrimp safe, but often times when this question comes up on forums rasboras come up as the most-likely candidates.  I would think that once they figure out there are flies on the surface they'll have a little feeding-fest and knock them out in days, after which time you could transfer them back out.  I'm hoping your experience is like mine in that once the flies were eradicated, they never came back.  This occurred on my first tank immediately after set up when I moved shrimp to my basement area, and hasn't occurred on any of my other 7 shrimp tanks now on the same rack.  

 

If you do try the rasboras, please let us know how it works out.  This problem seems to come up infrequently but I know I hated it, and was willing to consider all options to fix the issue.

 

Thanks. I will provide an update.

Going to check out a few LFS over the weekend to see if I can find that Hockeystick pencilfish. If I can't find it, then I'll try the Rasboras.

 

[aquaprawn]

Okay, as promised, here's the update.

 

I'm unable to find Hockeystick Pencilfish. So I placed 6 Chili Rasboras into a quarantine tank for suitability observation.

 

I noticed that they tend to occupy the mid to lower zone, so this is not ideal as the larvas are usually on the upper zone. And they might pose a threat to the PRL babies lurking on the substrate. Secondly, I placed a few larvas into the tank to see if the Rasboras would snap them up. Unfortunately they are not very enthusiastic. The six of them looked at the wriggling larvae and ignored it - none actually took a bite. These were quite disconcerting, so I decided not to put the Rasboras into the tank.

 

So I had to try another method. I placed mosquito repellent just a few inches behind the tank. Its the Citronella based air freshener. Over the next few days, I noticed a dramatic drop in the adult flies lurking on the surface of the tank - presumably repelled by the Citronella scent. There are still larvas in the water, but I hope when the adult fly emerges, they will not come near the tank. Fingers crossed, it will solve the problem.

 

Thanks.

 

[LesterBee]

13 hours ago, aquaprawn said:

Okay, as promised, here's the update.

 

I'm unable to find Hockeystick Pencilfish. So I placed 6 Chili Rasboras into a quarantine tank for suitability observation.

 

I noticed that they tend to occupy the mid to lower zone, so this is not ideal as the larvas are usually on the upper zone. And they might pose a threat to the PRL babies lurking on the substrate. Secondly, I placed a few larvas into the tank to see if the Rasboras would snap them up. Unfortunately they are not very enthusiastic. The six of them looked at the wriggling larvae and ignored it - none actually took a bite. These were quite disconcerting, so I decided not to put the Rasboras into the tank.

 

So I had to try another method. I placed mosquito repellent just a few inches behind the tank. Its the Citronella based air freshener. Over the next few days, I noticed a dramatic drop in the adult flies lurking on the surface of the tank - presumably repelled by the Citronella scent. There are still larvas in the water, but I hope when the adult fly emerges, they will not come near the tank. Fingers crossed, it will solve the problem.

 

Thanks.

 

 

I'm going to venture that using a strong odorant/repellent, especially if you power your filters with an airpump, is not a good idea with shrimp.  The reason because the chemical that is released into the air will be drawn into the tank with the air bubbles, and dissolved into the water, possibly sickening or even killing the shrimp.

 

I'd get it out of there ASAP.

 

  The fish you want to use as the gnat larvae eater crew is called Nannostumus Eques, the Diptail or Brown Pencilfish.  See if you can get a small school of them (5~7) as they actually do better with few members to school with.  The problem being with these guys is that once they've eaten all the gnat larvae they may start going after the smallest of your shrimp, they also will load down you bio-filtration and cause a rise in Ammonia/Nitrites/Nitrates.  They also require a bit higher temperatures above 75 degrees at the least, they're happier at 78 to 80 degrees, as they are fish the from Equatorial Amazon basin.  Best if you can borrow a few, for a month or so. I'm not sure what friendly arrangements you can make with your LFS to solve this though.

[aquaprawn]

Oh yes, I think you have a good point about the air pump thingy. This means I'll have to continue to look for that fish..

Thank you for your advise.