Re Housing lots of Moon Wrasses And Not A Hoax/Bob's Input Please
3/13/09
Hi James,
<Hello Karen>
My thesis is actually a scientific one. I'm isolating anti-feeding metabolites from invertebrates and I'm using Thalassoma lunare in my feeding assays. Also, this species of Moon Wrasse is common in our country.
If you don't want to dive and buy it from suppliers, it cost around 30 pesos ($0.60), its pretty cheap, actually.
<All making more sense now, did not know your location as your English does not dictate such.>
My friends are willing to lend me two other 50 gal tanks, so now I have four. Sand and rocks? I can buy them cheap also. Since Thalassoma lunare is a tropical fish, do I still need heating?
<Likely not in your location. They would tolerate temperatures as low as 72F, but likely not too happy above 80F.>
I am actually worried it might die of heat, it's summer here!
<You may need to keep this in an air conditioned room.>
I need to buy a filter though. My problem is actually to keep them alive for about 4-5 months without them killing each other or dying. For the dividers, I need to group them for replicates, so I was thinking to group them even before I use them in my assay. So it's a not a good idea after all?
<If you divide your total gallons (200) by 40 wrasses, that's only giving them 5 gallons of space each, not nearly enough to expect any long term success. The tanks would have to be covered, as they would
jump, then with no escape possible, environmental stress would set in likely leading to their demise. I'm thinking you will be wasting your time.>
And don't worry this isn't a hoax.
<Mmm, maybe not a hoax, but not a workable plan, at least in my mind. How about in yours, Bob?>
<<Mmm, this Thalassoma species lives in harems... one adult male... dominant, with perhaps a few trailing females and juveniles... I don't know of a practical way to house a bunch together in one system w/o real trouble. RMF>>
Thanks.
<You're welcome. James (Salty Dog)>

Re: Housing lots of moon wrasses
Karen, James, Bob,
With my zoologist cap on, can I just add my two-cents' worth? Karen: if you're going to do any sort of experimentation on animals, you need be able to demonstrate that you've controlled all the variables. Specifically, you need to eliminate anything that might affect whatever measurement(s) you're taking. So if you're analysing growth rate of wrasse as related to, say, temperature, you need to make sure that social behaviour (crowding effects) aren't affecting the growth rate, or that metabolite concentration in the
water isn't affecting growth rate through toxicity. You need to be able to say that (in this case) temperature alone accounts for the changes in growth rate you've seen, and not bullying or nitrate poisoning. For practical reasons, most studies on fish use small species -- guppies, gobies, sticklebacks, convict cichlids and so on -- simply because it's easier to control all the variables. That's why we know more about these fish than whale sharks or sturgeons! If you're specifically interested in wrasses, there is a literature on some of the European species, for example through their use as "cleaner fish" on salmon farms. So you might want to find out how these fish were handled and maintained before coming up with
your own protocol. Otherwise, find some other small, cheap, available fish that might work better. Cheers, Neale.>

Re: Housing lots of moon wrasses
Hi Neale,
Thanks for your reply. I'm not planning to do any growth rate measurements or any of that sort. My objective is to prove that my invertebrate have anti-feeding metabolites. How? I'll extract these metabolites, incorporate them in a food matrix, make them look like food pellets and see if these
pellets are palatable to the fish. My control is food pellet without extract. As for my moon wrasse, I'll get them in just one reef location where I'll be getting my invertebrate, to eliminate any possible location
effect error. Also, I'm using wrasse because it's a generalist predator of benthic invertebrates.
<Hello again. While your idea sounds workable, I still think wrasse will be too big to make controlling the other variables easy. You'll have enough work isolating each metabolite, determining effective concentrations, looking for combination effects of two or more metabolites, and so on. I'd imagine a smaller fish, like a goby or flounder, would work much better.
For example, you could feed gobies live brine shrimp. By adding or not adding dosages of a particular metabolite, you could determine whether the presence/absence of that metabolite had any impact of feeding rates. Flush the water out, starve for 24 hours, and repeat as required. It would be easy to keep gobies in 5-10 gallon tanks, and since they feed on small particles but in large quantities, you could video tape their behaviour and get sufficiently large numbers of data points to actually do some serious
statistics. Do have a look at the classic Optimal Foraging work done using Sunfish and Daphnia; while not identical to what you're trying to do, in terms of practicalities and statistics, I'd imagine it would be relevant.
Cheers, Neale.>

Re: Housing lots of moon wrasses
Hi Neale, Thanks for your reply. That will be good because it would be easier. Regarding on the concentrations, I am particularly interested if the natural volumetric concentration of metabolites can deter feeding of the wrasse.
<May well do for all kinds of reasons. A small amount of a "prey" smell could indicate food, but in large quantities, a potential predator, or at least a predator feeding. So there are likely threshold values below which there's no response, a peak value the elicits the strongest response, and then amounts where the response either doesn't increase further or declines.>
For the starvation, I will not starve it, I'm doing my feeding assay an hour after its daily feeding.
<OK. But you'll have to demonstrate why this time interval was selected.
For zooplankton feeders like gobies, feeding likely occurs all day, and the stomach/gut morphology reflect that; opportunistic predators by contrast may be adapted to consume large amounts of food at one sitting, and then may not feed for some hours, even days, afterwards. Hence, a period that would starve species X might be simply a breather between meals for species Y. Assuming this is an MSc or PhD-level project, your examiners will presumably expect you to have demonstrated the optimal period between feeding sessions to elicit the strongest feeding responses (i.e, animals feed more, take more risks in terms of leaving shelter, the hungrier they are).>
This is to make sure that they are just not feeding out of hunger.
<What other reason is there for feeding? Do wild animals feed simply because food is sitting there? To feed optimally, they need to balance the risk of being exposed to predators against the benefits of consuming the energy source available. What you'll end up looking at, I suspect, is not innate desire to eat, but rather, do certain metabolites dissuade animals to feed despite being hungry.>
I actually based my methods on a paper. Please see the link
(http://people.uncw.edu/pawlikj/1995MEPSPaw.pdf)
This method is used by the same author in his other studies and when I looked at other studies, other researchers also used this, so it's like a standard procedure.
<Cool. It's always easiest to follow someone else's protocol, while changing a single variable to match whatever you're interested in. But still, be open minded: if the work has been done to death, there's no
mileage in doing it again. But if there's a reason other researchers could be mistaken, or if there's a factor they've not investigated, that's how you do good science. Anyone can follow a recipe; good cooks create their own! Cheers, Neale.>

Thalassoma purpureum 9/26/08
I am currently on waiting list for the Surge Wrasse (Thalassoma purpureum) at my LFS, Marine Center and Zooquatics.com. I wanted to get a better idea on feeding, care and handling of this fish, as there is very limited info out there, even on your site. Thank you in advance.
Charles
<Mmm, needs room, clean water, vigorously moving, high DO... high RedOx... feeds largely on small fishes and invertebrates, accepts most all meaty fare in captivity... More here: http://fishbase.org/Summary/speciesSummary.php?ID=5647&genusname=Thalassoma&speciesname=purpureum
Bob Fenner> 

Re: Thalassoma purpureum  9/27/08
DO?
<Sorry re: Dissolved Oxygen... as you are likely aware, this species lives in areas of high, consistent gas availability>
From what I've read, it seems otherwise to be a very hardy and unique addition to a FOWLR system, yes?
<Can be. B>

Triggerfish has become unsocial and not eating... sys. /env.    5/2/08
Hi Crew,
I've read some of your answers to other problems (and i am definitely looking here first for all my fish info!) but unfortunately I haven't quite got the answer that I'm need for this situation...
I have a 50-gal tank and all the levels are good. and there are many rocks, plants, and hiding places. I currently have 5 fish living in this tank, two 4-stripe damselfish, a blue devil damselfish, a 3 1/2 inch lunar wrasse, and a 3 inch rectangular trigger fish.
<The last two need more room than this...>
The wrasse is the newbie in the tank and he is doing really well. but before we got him, trigger was king of this tank and for the first couple days that the wrasse was introduced, the trigger would get very protective of his side of the tank and would chase him all over. and then they co-existed peacefully for about a week but for the last 4 days or so trigger has been MIA... he is hiding all the time and not been coming out to eat the frozen pieces of krill that he loves.
<Not good for a standard diet>
the wrasse doesn't bug the damsels at all, he just likes to swim all over. but the times that i do see trigger (when the tank light is off but the overhead light in the room is on and the fish are "sleeping") i can see glimpses of trigger
moving to where he sleeps. at this i see an opportunity to feed him, but as soon as he sees me he goes back into hiding. I'm afraid that he is going to starve. should i take the wrasse out?
<Perhaps>
i have another 10-gal tank that has 2 ocellaris clown fish and a scooter blenny in it
<... also need more room>
but i think that tank would be too small and he would be unhappy. the other solution i thought of was to sell back the wrasse the fish store but that also doesn't grantee that trigger will go back to normal, plus I enjoy watching the wrasse 'fly' throughout the tank. i hope this is enough info and any help would be greatly appreciated!
-Jamie-
<Well... you seem to be aware of your options. Going forward, I'd either get much larger tanks, or investigate the psychological needs of the livestock you intend to keep... These systems are too crowded. Bob Fenner>