Systems and methods for the electric field controlled anesthetizing of fish

Abstract

A system and method to induce fish anesthetizing or narcosis is described that induces a potential field across the body of a laboratory fish having a pair of electrodes, the waveform generated by this potential field is approximately balanced to reduce the introduction of anions into the solution, and a camera is mounted to observe the activity of the fish, so that the potential difference may be adjusted based on the state of the fish.

Claims

1. A method for inducing an electrical potential difference across a fish species, the method consisting of: creating a potential difference in a body of water across an anode and a cathode of a fish tank, said fish tank having the anode and the cathode spatially placed at the opposite ends of the fish tank; detecting the fish species in the body of water by a detector; mapping the detected fish species through a species to voltage mapping device, the species to voltage mapping device further comprising a database of a plurality of prestored species electrical waveforms; wherein selection of a prestored species electrical waveform from the database of a plurality of prestored species electrical waveforms is operably downloaded into the programmable power supply; varying the potential difference according to the selected prestored species electrical waveform so that the fish species experiences a physiological change.

2. The method of claim 1, wherein the physiological change experienced is electrotaxis.

3. The method of claim 1, wherein the physiological change experienced is electronarcosis.

4. The method of claim 1, wherein the physiological change experienced is electroeuthanasia.

5. The method of claim 1 wherein the maximum potential difference is greater than 5.0V across the body of fish.

6. The method of claim 1 wherein the species electrical waveform has a periodic waveform with a frequency from 0.1 to 1000 Hz.

7. The method of claim 1 where the species electrical waveform is an impulse.

8. The method of claim 1 where the species electrical waveform ranges from 1.5V/cm to 2.5V/cm across the body of each fish.

9. The method of claim 1 where the potential difference between the anode and the cathode is increased in a cyclic manner.

10. The method of claim 1 where the potential difference between the anode and the cathode is decreased in a cyclic manner.

11. The method of claim 1, further employing a top protector to prevent access to the fish tank when inducing the electrical potential difference across the fish species.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a system diagram of the laboratory fish anesthetizing system.

(2) FIG. 2 is a waveform diagram of a single pulse with a continuous positive and negative opposite polarity lobes.

(3) FIG. 3 is a waveform diagram of plural positive and negative lobes.

(4) FIG. 4 is a modified waveform diagram with a zero-field dwell portion interposed between the positive and negative field lobes.

(5) FIG. 5 is a system diagram of the laboratory fish anesthetizing system incorporating a proximity detector.

(6) FIG. 6 is a system diagram of the laboratory fish anesthetizing system which incorporates a programmable database of voltage waveforms that are species and/or subject specific.

(7) FIG. 7 is a flowchart of the laboratory fish anesthetizing system which incorporates a programmable database of voltage waveforms that are species and/or subject specific.

(8) FIG. 8 is one physical configuration of the laboratory fish anesthetizing system.

DETAILED DESCRIPTION

(9) Representative embodiments according to the inventive subject matter are shown in FIGS. 1-8, wherein similar features share common reference numerals.

(10) The term fish refers to experimental fish used in a laboratory setting, which include, but are not limited to zebrafish. These fish typically belong to, but are not limited to, the taxa group Telostei or Teleostomi. The teleost fish include such fish as zebrafish (Danio rerio), medaka (Oryzias, sp.), fathead minnow (Pinephales promelas), or goldfish (Carassius auratus). It is well established that fish have a typical response to electrical fields applied in the water, although each individual fish and each type of species may have a varying response.

(11) The term tank is generally known to those in the arts as a water tank, the preferred embodiment being a 10-40 gallon tank used by researchers that customarily sets on a laboratory top. Tank can also include larger tanks including outdoor tanks and naturally occurring ponds and streams. Also, the characteristics of the water should not be limited to freshwater, but, may also include water of differing salinities including sea water.

(12) The term electrical stimulation refers to an electrical field impressed on the tissue of a fish in water. This electrical field will have a range in values that is dependent on the age and species of the fish.

(13) The term programmable voltage supply shall mean a device that can output a range of voltages and currents in a waveform that is programmed either by hardwire switch (e.g., a pulse generator) or by software (e.g. a computer controlled voltage generator).

(14) Now referring to FIG. 1, a system 100 is shown for the anesthetizing fish. The system 100 has a water tank 110, two electrodes 120, 120 immersed in the water tank 110, two wires 130, 130 connected to the programmable voltage source 140. The water in the water tank 110 is filled to the water level 180. The electrodes 120, 120 are typically immersed below the water level 180. When voltage is applied across the two electrodes 120, 120 a voltage gradient is impressed across the fish 160. Depending on the size of the voltage gradient induced in the fish will determine the effect on the fish.

(15) To anesthetize the fish 160, (electronarcosis), a voltage gradient of 150-250 V/m (1.5 to 2.5 V/cm) should be induced across the fish 160. To induce paralysis in the fish (electrotaxis) a greater voltage gradient than needed for electronarcosis should be induced across the body of the fish. To euthanize the fish 160, a voltage gradient of 1.5 to 5.0 V/cm or greater should be induced across the body of the fish 160. The voltage gradients needed for electronarcosis, electrotaxis, and euthanasia vary from fish species to fish species, and of course, differ based on the individual physiology of each fish.

(16) In the laboratory setting, the water tank 110 will usually have dimensions of 2 feet in width, 4 feet in length, and 2 feet in height, holding the total water volume of 8 cubic feet or approximately 60 gallons. Freshwater conductivity in a laboratory tank ranges from 100 to 5000 S.

(17) As previously mentioned, a fish typically used in laboratory biological studies is the zebrafish. Mature zebrafish grow to a size of approximately 6.4 cm. Juvenile zebrafish, which are more commonly used in research, range in size from approximately 0.9 to 1.5 cm.

(18) The voltage potential varies as a matter of time and may be positive or negative on either electrode. Alternating current may also be used so that there is an equal balance of energy of time between the electrodes.

(19) Now referring to an exemplary waveform as shown in FIG. 2. FIG. 2 shows an impulse waveform at the electrodes 120, 120 (as shown in FIG. 1) such that the impulse voltage Vmax 250 and the impulse voltage Vmin 260 are during the time period t 230. This impulse voltage Vmax 250 and impulse Vmin 260 should be of sufficient strength and duration to induce the physiological effects (e.g. electrotaxis and/or electronarcosis) on the laboratory fish.

(20) Another waveform as shown in FIG. 3, with a periodic electrical potential waveform between the electrodes 120, 120 (as shown in FIG. 1) such that the periodic voltage Vmax 350 and the periodic voltage Vmin 360 are during the period time t 330. The periodic voltage Vmax 350 and the period voltage Vmin 360 should be of sufficient strength and duration to induce the preferred physiological effect (e.g. electrotaxis, electronarcosis, or euthanasia) on the laboratory fish.

(21) Another waveform as shown in FIG. 4 with a periodic waveform between the electrodes 120, 120 (as shown in FIG. 1) such that the dwell voltage Vmax 450 is separated by a dwell voltage Vdwell 470 and then followed by the periodic with dwell voltage Vmin 460 during the time period t 430. The periodic voltage with dwell should be of sufficient strength and duration to induce the physiological effects (e.g. electrotaxis and/or electronarcosis) on a laboratory fish.

(22) Now referring to the system as shown in FIG. 5, depicting a programmable voltage supply 140 connected to the electrodes 120, 120 that are immersed in the tank 110. The programmable voltage supply 140 is also connected to a proximity detector processor 520 and a proximity detector 510. The proximity detector 510 is used to determine if the fish 160 is close to the electrodes 120, 120. If the fish is in close proximity to the electrodes, then the output waveform (see FIGS. 2,3,4) is modified to prevent injury to the fish 160 either by diminishing or eliminating the range of voltage from the programmable voltage supply 140.

(23) Now referring to the fish anesthetizing system which is shown in FIG. 6. FIG. 6 depicts a programmable power supply 140 connected to electrodes 120, 120 which create an electric field in the tank 110 and across the fish 160. Connected to the programmable voltage supply 140 is a species to voltage mapping device 610. The species to voltage mapping device 610 stores a database of species electrical waveforms in a database 620. This database is updated by the input device 630.

(24) The operation of the fish anesthetizing system of FIG. 6 is shown in the flowchart of FIG. 7. A species 720 or subject 730 waveform is selected and is loaded from a database 740. This waveform will have a voltage range and characteristics induces either electrotaxsis or electronarcosis in the fish depending on the desired effect on the target species. Likewise the voltage range and characteristics depending on the subject profile, for example, if it is known that the target fish is a minnow that is 2 cm in length, this characteristic can be preselected from a database. Once the database voltage is selected it is transferred (i.e. downloaded) 750 from the species to voltage mapper to the programmable voltage source.

(25) Now referring to FIG. 8 that illustrates one configuration of the physical implementation of the laboratory fish anesthetizer 810. The system has a storage unit 820 that contains the electronics and associated power supply. The storage unit is connected to the electrode supports 830 which are integrated with the length supports 850. Interconnecting the two length supports are two width supports 840. The length support 850 can be expanded lengthwise 855 to accommodate tanks of varying lengths. The width support 840 can be expanded widthwise 845 so that tanks of varying widths can be accommodated. Optionally present is a top protector 860 so that access to the top of the laboratory water is blocked.

(26) The system in FIG. 8 may be configured to prevent access to the water in the tank while the apparatus is operating. Those skilled in the arts will recognize that interlocking switches may be employed so that the electrodes 120, 120 of the laboratory fish anesthetizer 810 are not energized if power is applied

(27) Persons skilled in the art will recognize that there are a wide variety of databases that can used to store signal patterns, including, but not limited to SQL databases, text databases, or object oriented databases. Persons skilled in the art will recognize that there are a wide variety of programmable voltage supplies, including, but not limited to products manufactured by Lamda (Neptune, N.J., USA). It is also understood by those skilled in the art that the database and/or the programmable power supply may be implemented in firmware in a manner to reduce and/or minimize costs.

(28) Persons skilled in the art will recognize that many modifications and variations are possible in the details, materials, and arrangements of the parts and actions which have been described and illustrated in order to explain the nature of this inventive concept and that such modifications and variations do not depart from the spirit and scope of the teachings and claims contained therein.

(29) All patent and non-patent literature cited herein is hereby incorporated by references in its entirety for all purposes.