Solving hydroid problems

F

FuEl

New member
Hi people,

I've been experiencing some problems with hydroids in my recirculating larval grow-out system. I've read up on Panacur as apparently it is used for seahorse fry. But my concern is whether it would be safe for crustacean larvae? Are there any other ways of controlling them? If not I'll probably have to totally scrub out the larval grow-out tanks every few days. The water input is now screened using a 100 micron nylon mesh so I'll be seeing if that helps. I've heard of people talking about hydroids being introduced with brine shrimp but I seriously doubt it as I soak my bbs in FW for about 10-15 mins before usage.

Many thanks. :)
 
I have seen hydroids live through 24 hours emersed in fresh tap water. I pulled a seahorse fry bowl and filled it with tap water and the next morning the hydroids were still there. With the fish bowls I always bleach them to be sure. I have used Panacur for hydroids but only after removing the seahorse fry. I wouldn't risk it with invert larvae.

Bruce
 
Agree with Bruce,this pest is tough,copper does not affect them|:eek1:
Dunno how to kill them,never tried Paracure.I scrap the polips from smooth surfaces and siphon them.And pipette the medusae one by one:rolleyes:
Better to avoid them filtering all water to be used in larval tanks and formaline bath demersal nests.
 
MY hydroid problem seems to run in cycles. I've never really tracked it but I'll go months without seeing one then I'll spend the next month sieving out tank after tank after tank of them. Tough little buggers too, I've tried a couple of things on them to no avail, so now I use a 53m screen to grab them up. way faster than pipetting them.
 
Thanks folks. Seems that I would be stuck with hydroids for quite awhile. I'll see how the 100 micron mesh works out. Hopefully it is small enough to catch the free swimming medusa. If not I'll probably have to utilize my precious rotifer mesh. :strooper:
 
Me personally, I'd have to test the panacur out on the crustacaen larvae. I'd have to know. My gut says it won't harm them; as its not meant for crustaceans. But then again, the larvae are so sensitive, who knows . . .

I really doubt hydroids come on bbs eggs. I've seen that theory passed around and it just doesn't make any sense as there is no point in the hydroids' life cycle that would have evolved to do that.

However, if you really feel they might be coming from the eggs, a short rinse in chlorine bleach may be the answer. I can't remember exactly how to do it, but look up decapsulating bs eggs, and just do it for a much shorter time.
 
Hi FishGrrl, kindly let me know of your findings if you do decide to try? :) I've read that Panacur will kill corals so I am rather uneasy on trying it out on crustacean larvae. :rolleyes:

I'll be ordering some decapsulated bbs from brineshrimpdirect soon so I should know soon enough if hydroids are introduced with bbs.

I have this feeling though, that the hydroids come from our tank water which most people use to hatch bbs. Most people I know of don't filter their seawater before using it to hatch bbs. When they harvest bbs, hydroids would be present as a result due to contamination with seawater taken from the tank. When they feed this mixture to their larval tanks and hydroids take over, brine shrimp eggs are unavoidably linked to this. Perhaps hatching bbs with newly mixed seawater/heavily filtered water would be a great way to discover if this is true? :rollface:
 
Fishgrrll and FuEl are right.Hydroids coming in the bs eggs must be a urban legend,as cnidaria don´t have any kind of desiccation resisting strategies.
 
With what Luis had just said, looks like I might be putting the order of decapsulated cysts on hold for now. :)

Another thing worth discussing. Anyone has any idea how large the free swimming stage of hydroids are? I have this paranoid feeling that 53 microns might not filter them out. If only I had a 5 micron sieve now. :lol:
 
<a href=showthread.php?s=&postid=8011588#post8011588 target=_blank>Originally posted</a> by FuEl
With what Luis had just said, looks like I might be putting the order of decapsulated cysts on hold for now. :)

Another thing worth discussing. Anyone has any idea how large the free swimming stage of hydroids are? I have this paranoid feeling that 53 microns might not filter them out. If only I had a 5 micron sieve now. :lol:
Click to expand...
53 mic.will stop them.Small ones are about 500 mic.And they grow up to 2cm!
 
Hydroids come in on the brine shrimp eggs. You need to decapsulate your brine shrimp eggs. Very easy to do.
 
<a href=showthread.php?s=&postid=8013849#post8013849 target=_blank>Originally posted</a> by Sally
Hydroids come in on the brine shrimp eggs.
Click to expand...
Fact or myth,Sally?.They sure grow like a wild fire when we feed bs,but that´s because they feed on it.We used to think frogs came with the rain.:p
 
I'm beginning to suspect IA.
Closed looped systems for years, the only outside introduction to early period larvae for me is IA, rotifers, and salt.
So it's either in the salt mix (I highly doubt that), the rotifers (running continuously for three years) or the IA (frozen in ice cube trays).
1500 miles from the nearest ocean I've run out of suspects.
I've never fed BBS, never.
 
After reading through the many mind-boggling inputs, if I had a microscope with me now I would definitely do the following.

1) Soak some hydroids in FW over a few hours & return them to seawater. Then observe for any signs of life.

2) Observe hydroids being nuked(?) with copper sulphate.

3) Freeze some hydroids in the freezer then thaw them and see if they survive.

4) Hatch some bbs under clean sterile seawater and observe the hatch mix under the microscope for any hydroids.

At least it will be worth eliminating some myths or possibilities and narrowing down on the root cause. Sigh, living without a microscope makes one feel so helpless. :(
 
I did not mean to sound sarcastic,but the idea that hydroids come in bs eggs has been around for a long time and yet I never saw any reported evidence of that.If somebody could find any such evidence,please post it here.Check libraries or the Net to find if cnidaria poses any desiccation enduring mechanisms,such as eggs or cysts.
Because if they do,it would make sense that hydroids living in hypersaline ponds and preying on bs,had found a way to survive very high salinities and desiccation,same as their prey.
I have two species of hydroids.Both prey in bs,but not on pods or rots.But they devour small fish larvae :mad:
Even if they´re nasty and we hate them,they´re not without some charm under the diss.microscope.Some people like them and culture them for their delicate medusae.There was a Koralle issue dedicated to them.
I did steps 1 and 2 suggested by FuEl.I place a piece of hydroid scrapings in a tall Petri dish,and feed them with bs.In a short time they attach to the dish and spread all over.That makes changing water a breeze.The dish can be placed under the scope for observations on how they feed and reproduce.Several dishes can be used to try different treatments against them.
What we can all do,and then compare results,is setting a gallon jar or such with new asw and some air bubbling ,far from any possible contamination with water from our tanks.A small amount of eggs should be put to hatch,and periodically some few more could be added.Extra avoidance of contamination is key here.
Wether hydroids show or not,will allow us to solve this enigma!;)
 
Perhaps you are right Luis ...the hydroids do feed on the bbs. I am only basing this on my experience....and only my experience. It seems that when I have decapsulated the eggs I have not had such an issue with hydroids. When I did not decapsulate the eggs....they spread like wild fire. I will agree with your conclusion that they feed on the bbs.
 
I use ozonated, UV treated nsw and I still get them in my seahorse tanks that are fed enriched brine shrimp. I don't decapsulate my own brine anymore, but I do buy already decapsulated, hatching brine. I seem to get more hydroids in the summer so maybe there is a temperature relation? Anyone else notice them more in certain temps?

Christine
 
<a href=showthread.php?s=&postid=8023680#post8023680 target=_blank>Originally posted</a> by Luis A M

What we can all do,and then compare results,is setting a gallon jar or such with new asw and some air bubbling ,far from any possible contamination with water from our tanks.A small amount of eggs should be put to hatch,and periodically some few more could be added.Extra avoidance of contamination is key here.
Wether hydroids show or not,will allow us to solve this enigma!;)
Click to expand...
Well,I did it and hydroids didn´t show.:cool:
And I filtered/UV incoming water to a larval shrimp system heavily fed with artemia,and not a single hydroid appeared.
So I must conclude that hydroids coming with bs is an urban myth.
 
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