Reefs.org Forums

[SPC]

Glen, I am having trouble with your theory for this reason. How could anything but NSW conditions not be stressful for the fish? It would seem to me that after millions of years of evolution [img]images/smiles/icon_wink.gif[/img] that these animals need these conditions not to be stressed. I understand what you are saying, but I just don't buy it.
Steve

[cjdevito]

most of my stuff from LA comes in catalina water (NSW),

You might check it on a regular basis. I use CWC water myself, and I've found it's salinity fluctuates a bit over a year. Nothing too drastic, not like hyposalinity conditions, but it can get a bit low.

[newreefman1]

Mary you say you keep it at 1.023 in your "coral System"
Do you keep seperate systems and if not, how do you medicate any sick fish without affecting corals?
I know you have a new fish setup which im assuming is seperate from the corals since you want different salinities but whats the situation as of now?

Jason.

[MaryHM]

The fish have been kept in the coral system for the last 3 years. Granted, we don't do a lot of fish, but the fish we import are all GUARANTEED HAND CAUGHT. Makes a huge difference in the health of the animal. Knock on wood, we've only had a disease problem once when we brought in a net caught shipment from the Philippines. It's amazing how much healthier truly net caught fish are.

[Rover]

Stev,
It's a simple excercise in making the biology of the animal work for you. The ocean is not neccesarily the stable place we think it is. These animals are able to handle a wide variety of conditions. (The fact that they can live in a tiny glass box at all says something.) The temperature of the reef and the salinity are not constant. Being placed in a cardboard box and shipped cross country can hardly be considered NSW conditions either, so steps are taken to increase viability over the long haul.

Cooler water has more available oxygen, and it slows down the metabolism of the fish which cuts back on the amount of waste pollution in the bag. Not something you would want to do long term but it has benefits over the short term.

Hyposalinity also increases the oxygen and kind of has a "calming" effect on the fish which is also beneficial during shipping.

Flowers are kept in coolers to keep them fresh and saunas can be good too but only short term.

Glenn

[JeremyR]

<<Something about it being easier for them to osmoregulate in lower salinities? Marine fish being hyposmotic (the ocean is saltier than thier innards) constantly have to drink water to keep from dehydrating. As the salinity of the water is lowered the gradient between outside and inside becomes less and osmotic stress is reduced. There is no reason to maintain this long term, but when a fish already has a million other stressors placed on it from shipping process it seems that being able to reduce one area of stress would be beneficial. The energetics of body maintenance are reduced allowing more "energy" to fight disease and parasites and infection. It's been a while since ichthyology so some one correct me if I've got it screwed up.>>

That's part of the theory.. but i don't buy it. If it was easier for htem to regulate their systems, then there would be no problem with long term survival in a low salinity.. but I don't think any of us would intentionally keep our fish long term in a hyposalinity situation. I've seen no evidence that this is beneficial, and I've known plenty of people who ran their tanks sub 1.020 that still had serious parasitic outbreaks.

[farmertodd]

And I'll toss another nickle in the cup and say that I've seen parasitic outbreaks of amyloodinium (marine ich) in 1.016-1.017 in systems where copper was dosed regularly, just prior to it needing a new dose.

And none of the foremention tactics does a bit of harm to crypto. In fact, that's kinda how I do a quick detect in a new shop to see if I would even want to consider buying any of their animals.

Todd

[liquid]

The temperature of the bag we have only some control over at best and since they're colder, yes, their metabolism is going to slow down too. However, I do not want a perfectly healthy fish subjected to hyposalinity conditions just b/c it has this "calming effect" as you call it and that it has an anecdotal (at best) effect on parasites. Why subject a fish to any more stresses than you have to? I mean, the fish is collected at NSW. It arrives at the wholesaler where it's SG is dropped by 22% and this happens to ALL the fish regardless if they have parasites or not so there's another added stress. The fish are then shipped to someone else where they have to be acclimated *again* to another set of conditions. Minimize the stress is my motto.

Also in regards to this "calming effect": is it really "calming" or is it a stress response and it only "looks" calmer? I mean, you subject a human to high altitude air and you bet it'll look calming as all he/she can do is just lay there and breathe as well as they can. Or if you subject a human to high temperatures he or she will just sit there too as it's too d@mn hot to do much of anything else. I think this "calming effect" that you're seeing is a stress response. Is a 1.018 sg even seen in their natural habitat? Only around estuaries and where there's a lot of land runoff and in those areas you see decreases in diversity.

Minimize stress = maximum survival rate

FWIW

Shane (aka 'liquid')

[Rover]

My question is how do we know that low salinity causes stress? What evidence is there that indicates that it does? Other than the fact that it is not what is found where they were collected?

Glenn

[liquid]

My question is how do you know that low salinity *doesn't* cause stress? These animals existed in a NSW environment *how long* and they're thriving? Why is it that every time someone suggests that perhaps mimicing natural conditions is a better answer than humans intervention, that they're the one put on the hot seat? Of course humanity can figure it out, *and do it better* in, oh, about 15 minutes! [img]images/smiles/icon_razz.gif[/img]

Let me use a real life example: let's say you've left your kids outside to play all week and then it rains for 4 days and they're going ape inside the house and then all of a sudden they're calm (i.e. lethargic). Would you not be concerned? Calm doesn't always equal less stress.

My $0.02...

Shane (aka 'liquid)

[Rover]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote

My question is how do you know that low salinity *doesn't* cause stress?

My point exactly. There doesn't seem to be any evidence on either side that it is harmful. (FWIW I maintain my store tanks at 1.025) I agree with the idea that we should mimic their natural environment as closely as possible. But the science backs up the fact that lower tempertures and lower salinities may reduce stress during the shipping process. I have never seen any evidence to refute this other than the statement "it's not the conditions where they were collected." That is a logical statement I've just never seen any thing else to back it up.

Glenn

[ December 13, 2001: Message edited by: Rover ]</p>

[MaryHM]

From http://www.wetwebmedia.com/spg_salinity.htm

"Fish only systems are frequently kept at artificially low specific gravities (1.017-1.020) commercially for three principal benefits. 1) Cost of salt mix is less; even "natural" water that has to be hauled may be diluted with fresh at a savings. 2) Parasite and microbial levels are reduced; they can't make the osmotic stretch as well as macro-life. 3) Gas solubility is enhanced; increasing capacity, health. The margin of safety in rapid-adjusting fishes to new spg is dependent on several factors, especially their adaptive state."

[MickAv8r]

Back in the spring I probably would have posted that we saw fewer parasites when we ran our fish system at 1.018. However we are just finishing our second year at NSW conditions (strive for 1.025, but can vary somewhat) with the corals and fish on essentially the same system (two separate systems plumbed together). This year I really made a conscious effort to ramp up the feeding. Now that I feed heavily the parasite outbreaks have been in check (absolutely nothing all summer). Our loss rate was most definitely higher from 'unexplained' deaths (stress most likely) when we ran hypo. Our losses in general are down dramatically since we went 'natural'.

BTW our coral tanks are lit with a variety of lighting, usually a combo of 175W or 250W MH and/or PC's. We use different combos not only to have different intensities for different corals, but so that customers can get some idea of the type of lighting they want i.e. they can see side by side the differences between say a 250W 5500K bulb versus a 250W German.

[ December 14, 2001: Message edited by: MickAv8r ]</p>

[Tim Tessier]

Whether a system is run hypo(1.010 to 1.014) or at nsw (1.025 to 1.026) does not really make to much difference if the fish are from the Philippines or Indo. Fish from the Philippines, ime, usually have problems while the same species from the Sth Pacific don't. Another point to consider is the Philippines pack very light(small bags and minimal water) which seriously weakens fish. My Philippine shipments come in at a ph of 6.6 to 6.8 after a 30 hour trip in a bag. My Hawaii supplier packs heavy, lots of water and a big bag. Their fish come in with a ph of 8.1 after 24hours bag time.

I also keep my fish with my corals and run the system at 1.025 and 78f. For lighting I have 1HO daylight over a row of 15 gallon tanks. I have several 135gallon that have 2 ho daylight.

For acroporiids and certain other stonies I use 2 * 400 watt 10k german MH and maintain at 81f and 1.025.

For clams I use a 400 watt 6.5k Iwasaki, 82f and 1.025.

Cheers,
Tim

[Rover]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote

Now that I feed heavily the parasite outbreaks have been in check (absolutely nothing all summer).

I've noticed the same thing. I also noticed an explosion in sand critters as well. IMO an LFS should keep their systems at NSW conditions because hopefully that is what the hobbyist is maintaining and if not it may encourage them to start. My only question is whether or not it is beneficial to lower the salinity and temp for the a trip (overseas, or cross country). If that is the case it may be beneficial forthe wholesaler to maintain their systems a little differently.

Glenn

[olinf]

I know I will probably be flamed for this post but I just thought I would drop my $.02 in and play devils advocate. I have had much greater success in my fish-only breeding systems at a S.G. of 1.018 than with full strength S.W. Keeping a reduced salinity is in fact a key feature in inducing spawning. The larvae seem to respond especially well to lowered S.G. In side by side trials in my lab, I noted a 25-40% increase in survival and an 18-30% increase in individual growth rate in those larvae kept at a depressed S.G. Oxygen saturation and parasites did not play a role in the results, rather it appeared to be due to a decrease in metabolic workload by requiring less effort to maintain the internal salt level. Numerous other studies have also shown an increase in juvenile and adult growth rate and survival in marine fishes kept at lowered S.G. I believe that the argument that the environment in which they are found must be the best one is an overly simplistic view. There are many examples in nature of organisms that adapt to environments because habitat is available rather than because ideal conditions are available. A good example is found in the halophytes (salt tolerant plants typically found in estuaries) and mangroves. 70-90% of their metabolic energy is devoted to expelling the excess salt. Growth rate was increased dramatically when grown in low salt or even freshwater conditions. In the case of fishes, the ocean provides an abundance of habitat and it is believed by many that most marine fishes are evolved from freshwater fishes. So this may be a case of coping with seawater at 35ppt, instead of actually preferring it. In short, I don't believe that keeping marine fishes at decreased S.G. is intrinsically wrong, in fact it may even be beneficial. Rather, in the specific topic posed on this board, I think the real question would be whether a series of rapid S.G. changes from the ocean to the wholesaler to the retailer to the hobbyist would stress out the animal additionally, or whether dropping the salinity does in fact have a benefit by decreasing metabolic demands. I don't have an answer to that question, I just thought I might just toss a bit more fuel on the fire.
Olin