If you are picking up fish from the LFS down the street and the fish are only in transit for an hour, then a drip system is adequate, but long packing duration requires more delicate acclimation to ease the stress of extreme water conditions.
I still don't like the idea of floating fish bags as they may have medications and chemicals from a packing counter or holding tank (particularly copper). The fish are also stressed by the pinched corners of the bag and are forced to inhale oxygen from the surface as the bag rolls around in the water current. Bags can float under bright aquarium lighting, fish can pick on the new ones while they are still in the bag, and in some cases the bag collapses eliminating all gas exchange which can kill a fish quickly.
I think we all agree that the shipping water with the fish has no business in our systems. In addition to it containing chemicals and medications, it harbours bacteria and parasites and the water quality at fish stores is less than pristine. Every time a wholesaler imports a fish, he imports diseases that are unique to that part of the world and even that part of the reef. Fish stores are at the end of the chain of distribution and are therefore a united nations of fish fish diseases with every possible pathogen represented
In Peter's case as with people who buy from distant suppliers over seas or in another State, the fish will be in that shipping water for at least 24 hours. As the fish breathes it converts o2 into Co2. The Co2 is in a liquid form (carbonic acid) which, like any acid, lowers the PH. The longer the fish is bagged, the lower the PH. On one hand a PH of 6.7 - 7.0 is stressful to the fish, but on the plus side it takes the toxic ion out of ammonia rendering it harmless.
So now you receive your fish at home and the first thing you do is open the bag and let that "bad" air out and let "good" air in... wrong! As soon as a gas exchange occurs, the PH is rapidly driven back up to 8.0 - 8.2. This increase in PH is not only a shock to the fish, but a deadly poison as the toxic ion of ammonia goes back into solution. I've seen fish orders die in 20 minutes after travelling for 48 hours successfully
One solution is moving the fish directly into new water with matching parameters (PH, temp, salinity etc.). The small scale alternative is to add ammonia neutralizing chemicals such as Kordon Amquel.
http://www.novalek.com/kordon/amquel/index.htm Kordon has another helpful product called Novaqua that helps restore a fishes slime coat while removing nitrite, heavy metals etc.
http://www.novalek.com/kordon/novaqua/index.htm
The problem with drip systems is in the execution not the theory. People tend to use containers that aren't food grade so chemicals can leach out, especially when we are adding acid or oxidizers. LFS's have a bad habit of using dirty styrofoam boxes that have been used many times for everything from holding tanks to porta-potty, on both sides of the globe. Styrofoam containers are too bright (white). Fish are very sensitive to light during acclimation. Styrofoam containers are also to wide, requiring too much water to fill the bottom so LFS workers prop them up at an angle to concentrate the water in the corner. This works fine until it falls with the weight of the new water.
Another common problem is drip lines that stop dripping or drip too fast or fall out of the acclimation container and pee on the floor. Air lines are equally as problematic. Fish don't like the sound, air bubbles can cause nitrogen bubble disease (tiny air bubbles trapped in the gills), and air lines are notorious for floating up and out of the water. This may sound implausible for your pair of clowns you just brought home, but I'm talking about larger scale operations where you lose track of what you have and where it is. Working in the dark late at night (from an overseas flight) compounds the problem.
Drip systems also have an issue of jumpers. Shallow containers with fish darting around and smashing into each other is a recipe for jumping. It's like that hyperspace button in Asteroids for those of you ld enough to remember it (or young enough to have the capacity for long term memory). The fish hits the hyperspace button when things look grim (sorry brothers, no pun intended).
The ideal system for acclimating fish is a dark room with prepared tanks set at the parameters of the shipping water. Fish acclimate better to slightly higher water temperatures than they do to slightly lower temps, but i would go with the Goldilocks method of getting the porridge just right
Fish should undergo a maximum temp swing of 1F over a 24 hour period. The temp will likely be 68-72F so ice can be used to match it initially. Maintaining a cool temp over a few days can be a bit of a challenge without a chiller. Keeping acclimation tanks on a concrete floor or in a climate controlled room helps. The ice can be kept in bags if the salinity is already matched, but I have found that shippers usually have a hyposalinity (low salinity) of 1.017 - 1.019. From time to time they come in with a hypersalinity (high salinity) so salt should be pre-dissolved in a slurry that can be added to the acclimation tanks. A low salinity helps reduce parasites and stressed fish will feel more comfortable than in high salinity where they need to constantly pump the salts out of their bodies. A salinity of 1.019 feels like 1.022 to a stressed fish. Fish also acclimate much better going into lower salinity water than into higher salinity water due to a reduced osmotic pressure. Keep in mind the fish will be stressed as the salinity goes up when they go to the display tank. This is why a regular water change over the three week acclimation/QT is a good idea.
By adding acid or Co2 to an acclimation tank or system you can slowly bring the PH up over 24 hours or longer for sensitive fish like puffers. Drips are hard to maintain for more than a few hours. I go with a hybrid of mixing shipping water and acidified (PH corrected) water while acclimating shrimp and lobsters. Anemones are another one that need lots of time to adjust, particularly when they turn themselves inside-out. The key is to maintain excellent water quality (no ammonia or nitrite and high levels of dissolved oxygen) while acclimating. Sometimes a drip or hybrid system can't give you the optimum water conditions and stress-free environment the fish need.
Big commercial orders often take 6-12 hours to unpack so the temp and PH can shift while you work. I check a sample bag in every box to make sure I'm still on target. The boxes from The Philippines are double boxes with one on top of the other. During winter months the bottom box can be 5 - 10F cooler than the top box (especially if you use Northwest Airlines who fly everything through Detroit). Each airline uses its own hub to route flights. Pick one that is direct and with a moderate climate. In the summer you can use an airline with a hub in Chicago, not Tampa, while in the winter Tampa sounds a lot more tropical fish friendly than Chicago. Another variation exists with different sized fish. Damsels ship with a small splash of water while large tangs, angels & butterflies ship with lots of water. The bags with lots of water will have a higher temperature as they have a greater thermal mass, thus slower to swing when exposed to the cold. Keep in mind, the fish are stuck on a runway in a tropical country for hours where they are exposed to direct sunlight, then a cool shipping compartment, and then whatever your local airport has to offer. It would be nice to pack a thermometer with a 24 hour memory in a fish box.
Once the acclimation/QT tank is ready, pull up a seat and start cutting bags with sharp scissors and remove each fish by gloved hand to an appropriate tank. Aggressive fish and fish that may transmit disease to each other should be segregated. As much as chromis look cool in a school, they should be isolated to prevent or at least isolate white band disease and vibrio which they are susceptible to. Clownfish also do best on their own to prevent the spread of brooklynella.
I've tried numerous methods of acclimation and have found that the PH correction method is the best for the long and short term health of the fish. Within a few hours the fish are up and swimming around, while the drip method leaves them laying on their side breathing rapidly for a few days. Once delicate gill tissue is damaged (ammonia burn or lack of oxygen) the fish may never fully recover.
