Burke Museum Home

Professional Services


IDENTIFICATION SERVICES

Members of the public, as well as researchers not trained in the taxonomy of fishes, often encounter interesting fish specimens that they are not able to identify. Such specimens may be collected on fishing trips, found dead on the beach, or be taken by other means. Some recent examples include a putative pirahna (it wasn't!) collected in a local lake, a California barracudu (Sphyraena argentea) caught on hook and line in the Duwamish River near downtown Seattle, an opah (Lampris regius) found dead on the beach, and a large (3 m) sixgill shark (Hexanchus griseus) found floating in Puget Sound and towed home by a kayaker!

If you encounter an interesting or unusual fish that you wish to have identified, you may bring it to the Fish Collection. If possible, you should freeze or preserve the specimen (see "Methods of Preserving Fishes") to keep it from rotting until you are able to bring it to the collection. Please contact Katherine Maslenikov, Collection Manager, to make arrangements before bringing us any specimens.

Sailfin Sculpin
Nautichthys oculofasciatus, Sailfin Sculpin
R. Lauth

Methods of Preserving Fishes

Permits

Before any collecting can be done, the collector or collecting party must obtain the proper permits from the appropriate local, state, or federal agencies. Contact the Fish Collection before any collecting is done to be sure the proper permits are in place.

What to Collect

In general, the following rule should be applied: try to preserve all fishes that come into the net or are taken by other means--do not waste anything. Do not throw away small specimens (the adults of many species of fishes are less than 3 cm in total length); a good size series is always preferable to numerous specimens of similar size. Large numbers of specimens of each species are desirable; one hundred individuals of a single species are often not too many and in some cases are not enough.

Fixation and Preservation

Frozen fishes may be brought to the Fish Collection but formalin fixation is highly recommended for all routine collections (specimens destined for certain specialized studies such as histological work may be fixed in various other ways). Specimens should first be killed by means of a chemical anesthetic such as sodium pentobarbital, hydrous chlorobutanol, MS-222, urethane or similarly acting substance. If possible, a small piece of muscle tissue or a fin clip from either a pelvic or pectoral fin should be removed and placed in a small vial of 95% Ethanol. If this tissue sample is not taken before fixing the specimen in formalin, then no genetic information will be available from the specimen. Take care to label the tissue sample so that it is clear which specimen it comes from.

Specimens should then be placed into a solution of formalin made up of one part commercial Formaldehyde and nine parts water. This solution is of sufficient strength to fix small fishes up to five inches in length in about three days, but larger specimens should remain in solution for a greater length of time depending on their size. Specimens over 10 cm in length should be slit in the belly with a sharp knife or scissors, or they should be injected (with a syringe or hypodermic) with formalin. This allows the fixative to enter the body cavity and keep the contents from spoiling. In addition, the body musculature of large fishes (i.e., specimens 30 cm or more in length) should be injected about every 5 cm or so to allow the fixative to reach the deepest parts, and the specimens should be left in formalin from five to seven days or more. After that time, they should be passed through several changes of water, over a period of two or three days, to wash out the formalin, and then placed in 70% ethyl alcohol for preservation. Remember to be careful when using formalin--it's nasty stuff. Also remember not to pour formalin down the drain. It must at all times be disposed of according to rather strict state guidelines.

Labels and Labeling

Labels, giving all essential data, should be placed in the jar with the fishes when collected. Accurate information about the locality is as valuable as the fishes themselves; specimens without proper data are of little scientific value. Labels should have at least the following information: exact locality, coordinates, nearest land mass, or reference to a town commonly appearing on maps; date collected; name of the collector; and any other information that seems pertinent, such as depth of water, method of capture, any and all ecological data, etc.

Labels should be written with a soft lead pencil or permanent black ink (e.g. a Rapidograph pen) on 100% cotton or linen paper. Do not use ordinary paper because it will disintegrate in the liquid. Do not use a ball-point pen--the ink in most cases washes off in a matter of days. Large fishes may be tagged, preferably through the lower jaw, with all essential data written on the tag, or a number may be used and the data recorded under the identical number in a notebook. Always keep a field notebook in which you record all the information about each collection made.