Healthy fish really don't get stuck onto filter screens. The firefish is a bit thin, but not terribly so. I see a lot of issues with stores keeping their specific gravity low, and then at home, the SG is higher. Fish do not acclimate easily low to high (they can however go from high to low in a flash). Do you know the bag SG and how it compares to the SG in your tank?
Jay
p.s. - here is my simple acclimation technique:
A simple acclimation process
The following process is one that should be employed for all normal acclimation of animals from one system to another.
1) If possible, determine the water quality values for the aquarium that the fish will be coming from and adjust the receiving aquarium’s values to a similar range. As mentioned, if the values can be made nearly identical, no acclimation process is even required.
2) The fish must be transported from one aquarium to another in a manner that minimizes additional stress. The fish should be kept in the dark, and supplemental aeration or oxygen must be used for any transport lasting longer than about 30 minutes. Heat or ice packs may be required to maintain a proper water temperature during long transports. If you have control over it, handle the transport container carefully to avoid exposing the fish to any undue physical shock. Remember that losses during transport are always skewed to the very end of the transport time, so delays must be minimized.
3) Once at the destination aquarium, turn off the tank lights, dim the room lights and float the sealed bag in the aquarium for 10 to 15 minutes. This is sufficient to equalize the water temperatures.
4) If you don’t already know the values, check the pH and specific gravity of the aquarium and the shipping water. Long-duration shipments (greater than 24 hours) need to be handled differently and are described below. Avoid any increases in specific gravity greater than .004 units—adjust the receiving tank’s specific gravity to match that in the transport bag.
5) Open the bag, and roll the top in on itself to form a floatation collar. Remove as much of the shipping water as you can while still keeping the fish in an adequate volume of water. Add to the bag a volume of aquarium water that equals 25% of the volume of water in the bag. (For example, if the bag holds 8 ounces of water, you would add 2 ounces of tank water.) The fish is now 20% equilibrated. Wait five minutes.
6) Remove enough water from the bag to reduce it to its starting volume, and now add a volume of tank water that equals 50% of the volume in the bag. Wait another five minutes.
7) Remove water from the bag a third time, again reducing it to the starting volume, then add a volume of tank water that equals 100% of the water in the bag (the bag is now 75% equilibrated). Wait five minutes.
8) Release the specimen into the tank. Most aquarists avoid letting any of the acclimation water enter their tank. If the animal has been released into a tank housing other fish, monitor them very closely for signs of compatibility problems.
