Ostracod Anomaly - II - 08/07/2005
I actually don't know what is causing it, its not the food source, I only feed my shrimps a little 2 times a week. Thanks.
<I wonder if perhaps they are feeding on plants or decaying plant material, or possibly algae....  Again, it might be worthwhile to employ a small predatory fish in this system and see if that controls the population.  Wishing you well,  -Sabrina>

"A Craw-Fish by any other Name would Chew Plants..."
Mr. Fenner:
I am in the early stages of preparation for building my first community tank. I am planning a 35-Gal tank with many live plants and two species of schooling middle fish, one species of surface fish, and an additional species of bottom-feeding/Pleco-type fish. Is this feasible?
<Sure>
My main concern is this: I feel that in the future I may be unable to defend myself against the irresistible charms of lobsters and crayfish. 
<They are delicious... prepared properly!>
Is there a place in a perfectly harmonic community tank for one of these invertebrates?
<Mmm, no, not really. There are some fresh to brackish crustaceans that are "better"... please read: http://www.wetwebmedia.com/shrimpfw.htm>
I hear that they have picky tastes in water pH and temperature, are destructive to aquatic landscaping, and can be determined to bust out and go AWOL. Is there a way to have fish AND yabbies?
<Again... not really... their tastes are actually "too cosmopolitan", and many species are known to be quite "eury" condition... adaptable to widely varying conditions... but most all what folks call "lobsters", crayfish, crawdads, ditch "bugs"... are all too destructive, fish-eating to be "harmonious" in a community tank... Maybe two tanks? Bob Fenner>
Please advise.

Crayfish
Starting from scratch here.  We have success in sustaining crayfish.  We have had zero success in growing the tank population.  What could we be doing wrong?
<Likely the ones there already are eating each other. Especially when they molt (shed their external skeleton, to grow) crayfish are very susceptible to predation. Maybe adding more rockwork, some plants (plastic or real) will help boost your population. If you're expecting them to reproduce, there are a number of reasons why their young may not be being produced or likely being consumed as well. Bob Fenner>

My Little Lobster (terror!)
Hello,
I hope you can help me! I recently rescued what I believe to be a lobster from a friend who had moved it to a TINY tank after it removed the tails from all of his fish! It is about 3 inches long (when my friend bought it he was told it would grow to about a foot long) and resembles a crayfish at the moment but has a bluish tinge to it. My clever friend seems to know nothing about its care and I have spent the day searching bookshops and the web for info on how to care for it with no success. So I basically need as much info as possible or recommendation of a good book (which I can get in the UK).
<Mmm, sounds like a Cherax species. Please see here: http://www.wetwebmedia.com/FWSubWebIndex/fwcrustaceans.htm and use the names given for the identified animal a spin (insert) on your search engines. Bob Fenner>
Thanks very much
Sarah

Crayfish and goldfish in ponds
Hi, Do you happen to know if a crayfish would be good in an outdoor pond? Or would it eat my goldfish?
Zac Lohrenz
<Gage is apparently incognito... depending on the type of crayfish, size of goldfish... it might indeed be eaten... though I have seen these two species kept together. Bob Fenner>

I don't want copepods! FW crust. control.   3/15/08
Hi WWM,
I've searched your website for 2 weeks straight for information on eradicating copepods, but to no avail. Any info I find is in regards to how great they are and/ or how to cultivate them. I know that they are beneficial for fish to eat but i have what seems like thousands of them and i don't like them. Plus none of my fish eat them. I have a 75 gallon tank with 1 managuense,1 male and 1 female Dempsey, 1 green terror, 1 fire-mouth, and believe it or not live plants. I know that's too many big fish for a 75 but I will be transferring some to another tank when they get to large or aggressive. 0-Ammonia, 0-Nitrites, 10-15 ppm nitrates. 1 Marineland C-360 canister, and 1 Penguin 350 H.O.T. filter. I have so many copepods that it affects the water clarity. They are floating around everywhere. I do one 25-40% water change every week depending on the time I have. I want to know how to get rid of them without harming my fish. I know that some fish will eat them but my cichlids probably won't be too welcoming to any newcomers. Thank You very much.
P.S. Your site has a plethora of knowledge, and it's great for novices like me.
<Greetings. If you have so many copepods that you can see them, you likely have serious water quality problems as well. Truly, they will only multiply to big enough numbers to cause problems if they have lots to eat. Since they feed primarily on algae in the water column, your tank needs to be receiving lots of light and/or have high levels of nitrate and phosphate. Moreover, if the mechanical media isn't removing them physically from the water as it passes through the filter, then you don't have enough filtration. For large cichlids you should using filtration generating turnover of not less than 6 times the volume of the aquarium per hour. So add up the gallons per hour filtration for your filters and see if they exceed the magic number of 450 gallons per hour. I'm not a big fan of "hang on the back" filters though I understand they are for some inexplicable reason popular in the US. By gripe with them is they always seem to be a lot of plastic and plastic media modules but not a whole lot of actual media for their size/turnover. For messy cichlids, it's hard to beat standard issue external canister filters. In any case "the fault is not in our stars but in ourselves"; in other words, don't go after the copepods but try to establish why they're doing so well. Even if you somehow killed them off, for example with a copper-based anti-crustacean parasite medication, they'd likely come right back again after a few months. Cheers, Neale.>