SNB + Marine Micro Fauna - Brackish Water - Cirolanid Isopod

mattybecks

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I wasnt sure what heading to use for this question so I just put all the keywords in there. I have done research online but haven't found anything to be a solid enough answer.

3 Questions in short:

- Is Saltwater Nitrifying Bacteria (SNB) exactly the same bacteria as found in Brackish water? If so, at what point/salinity percentage do SNB colonize brackish water? Or is it predominantly FNB that are present in brackish environments.?

- What is the lowest salinity level micro fauna in a deep sand bed (DSB 12cm - 15cm depth) can survive? variety of different worm species, fan worms, sponges etc. Also, in brackish?

- Isopods. Any idea at what salinity these pods start to die off?

Why I ask, (if you are interested in long stories)

100gal tank - DSB calcareous rock and various other rocks (real live rock (coral rock) most of which was collected from the ocean here in Dubai. I love the bio-diversity of my tank, fan worms, sponges, crabs of all kinds (counted 6 different species thus far), all kinds of other worms I dont know names of, bi values, various types of pods (not parasitic), macro algaes, snails (limpits, turbos and others I cant identify) etc..you get the picture. Tank has been set up and established for about 2 years now. All was fine happy, and I didnt add anything new until end of last year (October). This was a clump of Graciela attached to calcareous rock, which I suspect the cirolanid isopods came in on.

So, I have a parasitic isopod problem. They must have been in my tank unnoticed for a little while since Oct, but in Jan this year they all of a sudden boomed and I noticed them. When I woke up at night, or in the early morning, all my fish would have a few on them. I was removing between 20 and 30 a night. This is of course stressful for the fish being constantly caught (the larger fish I could catch and couldnt hide in the rocks). No change in the Iso's population no matter how many I trapped or caught.

I didn't want to tear down the tank and destroy all the fauna I have, I didnt want to "nuke" my tank, but instead decided to use cyromazine (Microbe-Lift), which would sadly kill off all the crustations along with these parasites. I hoped. I did two treatments, doubled the dose on the second one. No more good pods left that I can see, crabs gone (all the smaller filter feeding ones I had that hid in the crevices) only one large white crab left I can see (which I actually didn't know existed until this week), and yet still these cirolanids remain. There numbers have reduced it seems, but they are still there. I understand they cant be killed once they reach terminal molt, so I have still been manually removing them at night, and I have noticed less of them, however I am still seeing some small ones of varying sizes which makes me think they are still molting. Although there are less, there seems to be a consistent amount each night no matter how many I had removed the night before.
I have added in wrasses about the same time I started the first treatment in Feb (rainbow wrasse and six line), which can help with the really tiny isopods, but the medium and larger ones they stay away from. (I had a third cleaner wrasse who was bigger and ate one of these isopods which then proceeded to burrow out of its stomach much to my shock and horror leaving it dead.)

I am at a point now where I realize I am going to have to change their environment to kill them as chemicals and predators don't do anything, I know this will come with a lot of death to my other micro and macro fauna sadly, but I want to save as much as possible. Hence the question of dropping the salinity to a point it might kill them. Although I am still half expecting to find out they can survive in freshwater too.

The main things I want to save is the SNB, The DSB and the sponge/fan worm garden I have.
 

Jay Hemdal

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I've not used cyromazine, but it is an Insect Growth Regulator that inhibits chitin synthesis. Like all IGRs, it is primarily effective against growth stages of arthropods. Those in a terminal molt would not be affected. When I've used other IGRs against Argulus (Dimilin), the adults are unaffected, but it keeps any new ones from developing properly.

Jay
 
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mattybecks

mattybecks

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I've not used cyromazine, but it is an Insect Growth Regulator that inhibits chitin synthesis. Like all IGRs, it is primarily effective against growth stages of arthropods. Those in a terminal molt would not be affected. When I've used other IGRs against Argulus (Dimilin), the adults are unaffected, but it keeps any new ones from developing properly.

Jay
Thanks Jay, I have noticed this happening with the other crustaceans in the tank, namely the tiny filter feeding crabs, however with the cirolanid isopods, although reduced in population, I am still finding them in all different stages and cycles of life. From small to large. I was thinking over time I would have at least stopped seeing the tiny, younger ones.

This is my first-time using IGRs so I don't have much experience, but in your experience, would you suggest I wait a bit longer, and do another double dose treatment and see how it goes? Maybe third times the charm. Just worries me I am still seeing small ones. I have no idea how long the life cycle of these isos is, or how long they stay in each stage of life. There isnt much info about this on the internet either.
 

Jay Hemdal

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Thanks Jay, I have noticed this happening with the other crustaceans in the tank, namely the tiny filter feeding crabs, however with the cirolanid isopods, although reduced in population, I am still finding them in all different stages and cycles of life. From small to large. I was thinking over time I would have at least stopped seeing the tiny, younger ones.

This is my first-time using IGRs so I don't have much experience, but in your experience, would you suggest I wait a bit longer, and do another double dose treatment and see how it goes? Maybe third times the charm. Just worries me I am still seeing small ones. I have no idea how long the life cycle of these isos is, or how long they stay in each stage of life. There isnt much info about this on the internet either.

Sorry - not having used that particular product, I can't do more than guess, and I don't like to do that with other people's tanks (grin).

Jay
 
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