How are baby fish fixed and preserved for storage after being collected in the field?
A. In order to fix or harden baby fish when taken alive from some collecting device in the field, straight unbuffered formalin (40% formaldehyde solution) may be poured into the collecting bottle with the mixed collection of plankton and baby fish. With this procedure, live or dying fish will be killed and fixed rapidly, often violently in the strong formalin. When using a live trap, a slurp gun or a minnow net, it may be preferable to first euthanize the baby fish with an overdose of an anesthetic such as MS-222 or Tricaine and then transfer them into dilute formalin or a high percentage alcohol. The bottles with the contained collections brought in from the field should be urgently attended to in the lab within several days. The collection should be put in a flat pie plate-like dish and using a flexible forceps, the baby fish can be picked out from the plankton and transferred into small glass or plastic vials. A label written with indelible ink should be added at this time. Then, di
