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Native Fish Conservancy
Informational Series Number 1
Konrad Schmidt, Editor
St. Paul, MN
This introductory packet contains the following information series which
should be helpful in getting your "feet wet" with natives.

Finny Critters Care and Maintenance. 
Fish Collecting Toys and Tips. 
Information Fishing Holes. 
Career Prospects. 
I. Finny Critters Care And Maintenance
Too Much TLC - The Editor's many hats includes a stint in a pet store selling
tropical fish. The most common problem which confronted novice Aquarists was
overfeeding their fish. Cloudy water and copious amounts of food accumulating
(and rotting) on the bottom were rarely acknowledged in time to prevent the
imminent disaster. Some well meaning fish keepers would feed three times a day
just like people when actually once a day is just fine and if you miss a day
or even a weekend - no problem. In fact, as long as it does not become a
regular practice. Fish are much tougher than they appear!

Carrying Capacity - One of the most frequently asked questions in fish
husbandry is how many fish can be comfortably maintained in an established and
filtered aquarium? A rough rule of thumb is one to two inches per gallon
(e.g., 10 - 20 inches in a 10 gallon aquarium). This guideline can be
exceeded, but the aquarium will require more frequent water changes and a
power failure or disease under crowded conditions can cause a major wipe out.

An Ounce Of Prevention - One very simple, safe, and inexpensive disease
preventive is the addition of salt to the aquarium water. Dosages range from
one-half to two teaspoons per gallon. Aquarium salts are available at pet
stores, however, non-iodized table salts are much cheaper and work just as
well. The only drawback occurs when aquarium water spills on the outside glass
and evaporates leaving a film which can be difficult to remove.

Landscaping With Rock - Many aquatic habitats contain rock which provides
structure and cover for fish. This natural and also attractive feature can be
realistically duplicated on a small scale in aquariums. Shale and limestone
are the easiest to work with and the latter also doubles as a buffer which
prevents the pH of water from going acid. The Editor favors contouring gravel
with rocks to form terraces which are honeycombed with crevices and caves for
fish. Live or plastic plants add a nice final touch on the upper level. Rocks
can be purchased from pet stores or collected from streams, lakes, or
quarries. However, avoid railroad beds where spills and leaks occur from a
myriad of nasty chemicals. I have heard several tragic tales from aquarists
who helplessly watched their favorite fish gasp its last breath shortly after
adding a pretty, but tainted stone or two.

Natural Vegetation - Live, aquatic plants provide cover for fish, reduces
algae growth, and also greatly enhances an aquarium's aesthetics. Several
species will work in the aquarium, but the grass-like, Valisineria (wild
celery), and bunch plant, hygrophilia, are two favorites of the Editor. I
prefer to purchase these from pet stores, but remember to leave the root crown
above the gravel with Val and remove any lead weights or rubber bands from
bunch plants. Plants also can be collected in lakes and streams, but restrict
harvests to early season when plants are actively growing. Late season
transplants, at least in Minnesota, often die back to the root system. Keep
lights on for only about 6 hours per day because longer photoperiods promote
excessive algae growth. Like fish, plants will need periodic water changes to
prevent water from getting too acidic. A 25% change once a month should be
sufficient. Finally, one plant to avoid is duckweed which floats on the
surface. To its credit, aquarium lights are nicely filtered through the
canopy, but no other plants can survive in the understory and once introduced
is almost impossible to eradicate.

Jumpers - Some natives have this suicidal tendency more than others and is
often most prevalent in the first few days of captivity. In Minnesota,
examples include the redside dace (Clinostomus elongatus), and both southern
(Phoxinus erythrogaster) and northern (Phoxinus eos) redbelly dace which the
latter, by the way, is often sold as jumpers in bait stores. The only solution
is a full hood on the aquarium, but sometimes a temporary cover restrains the
newcomers long enough to adjust and accept their new surroundings. 

Coldwater Tempering - Generally, floating new fish in an opened bag for about
20 minutes in the aquarium is sufficient time to equalize temperatures.
However, when collecting in trout streams or at northern latitudes in early
spring or late fall, much more time may be required to prevent losses. The
Editor uses a simple guideline: if there is more than 10 degrees difference in
water temperature, fish are put to bed overnight in a non-insulated bucket
with an air stone. The next day, if the bucket temperature is still too low,
begin partial water changes which are replaced with the target aquarium's

Those Other Things - There are several other fascinating organisms which
frequent fish environs that are either ignored or overlooked. Some work well
in community aquariums while others must be kept alone or with their own kind.
Some compatible critters include tadpoles, newts, snails, ghost or glass
shrimp, fiddler crabs, and small crayfish and mudpuppies. Another option is a
bug or macroinvertebrate tank. Streams, ponds, and lakes carry a myriad of
insect larvae, crustaceans, and zooplankton. Possibilities include larvae of
dragonflies, mayflies, damsel flies, stonefiles, caddis flies (junk bugs),
dobsonflies (helgramites), mosquitoes, midges, craneflies, water scorpions,
giant water bugs (warning-they bite), daphnia, scud; and fairy, opossum, seed,
and clam shrimp. Many of these bugs are predators and will happily prey before
your eyes on feeder guppies, goldfish, or minnow fry. Many zooplankton species
can be kept separately in very small aquariums and observed in incredible
detail under a microscope. For more information on the realm of possibilities,
refer to the Audubon, Golden, or Peterson Guides for reptiles, amphibians, and
insects. All should be available at most book stores.

Timers are very handy for many of us who are forgetful about turning aquarium
lights on and off. For as little as $6, this task is taken care of every
single day and also on vacations. Most timers have an override switch which is
handy for after hours viewing. One thing to remember - never plug the air pump
into the timer!

Stream Aquariums - Powerhead submersible pumps have been around for a long
time, but most are simply used on the top of an undergravel filter tube. Why
not try something just a little more creative? Next time the aquarium is
cleaned, insert the intake port directly into the filter plate and the outlet
nozzle pointed toward the front glass of the aquarium. If the fit is not
tight, try the adapters which come with the powerhead or use silicone to glue
it in place, but avoid plugging the intake screen. Make a sprinkler wand from
a rigid plastic tube (try pet stores) which should come within an inch of the
front glass and plug one end with silicone. Drill a straight line of holes
into one side of the tube which will direct current lengthwise across the
bottom of the aquarium. Select two slabs of limestone or shale which will fit
between the powerhead and the front glass and carefully sandwich the wand
between slabs. Lodge small rocks in the crevice to keep weight off the wand
and support the upper slab. Landscape with additional rocks to hide powerhead
and cover with gravel to fill in gaps. Fish will enter the current and find a
preferred velocity. Carpsucker and buffalo usually remain in a school
preferring the slacking currents farthest from the powerhead. While longnose
dace take turns charging the crevice where their bodies vibrate violently in
the high velocity turbulence. In large aquariums, two powerheads can be used
and the opposing currents collide in the middle. The only drawback is
powerheads greatly enhance the filtering capabilities of undergravel filters
and the gravel must be vacuumed on a more frequent basis.

Garden Ponds - Most native fish keepers have mastered the fine arts of
aquarium care and maintenance. Why not try something more natural? Not a great
deal of space is needed, even an unused corner in the backyard, but preferably
shaded. Probably the easiest thing to do is dig a hole for a children's wading
pool and add some gravel, rocks, and plants (Lilly pads and arrowheads look
great). Either air stones or small submersible pumps provide sufficient
dissolved oxygen in uncrowded conditions. Seeding flowers around the pool adds
a nice final touch. However, creativity knows no bounds and even more natural
ponds can be made with plastic liners. A friend of the Editor built a pond
with two bays that were connected by a small stream which actually flowed. A
rebuilt parts washer pump was used to draw water out of one bay up to a
waterfall at the other end. Native bog plants were also landscaped around the
exterior. All summer long, the back yard was filled with sounds of a babbling
brook, croaking frogs, and countless song birds checking out the new bird

Collecting Fish Foods - Ever consider shopping the great outdoors for several
types of live foods which are excellent treats or staples for native fishes?
Over a series of upcoming issues, selected tasty morsels will be critiqued.
First and foremost, glassworms, which are perhaps one of the better known
native grown food crops. However, they are not worms, but actually the insect
larvae of phantom midges (Chaoborus sp.) which are found in fishless ponds
from about the end of September into April (in the upper Midwest). During this
period, populations often become incredibly dense and are very easy to
collect. In the fall and spring, the only equipment needed are waders, a
large, fine meshed aquarium net, waders, and bucket. Twenty minutes of dipping
should produce enough food to last from one to several weeks. Winter
conditions requires some modifications which include an ice auger, smaller net
to fit through the hole, and an extension handle for the dip net to reach down
to open water. However, a little practice is required to develop the right
wrist action to efficiently scoop beneath the ice. As long as the water
temperatures are kept cold, but above freezing (33-50 degrees), glassworms can
be kept alive for several weeks. Refrigerators or unheated basements usually
do the job. Also, complete water changes should be done about twice a week.
The pungent odor and appearance of white (dead) worms indicate when it's time.
Glassworms also make an excellent frozen food and occasionally freezing
packets (ziploc bags are ideal) throughout the harvest season may cache enough
supplies to make it through the summer. One word of warning, pupae start
showing up in the spring and begin hatching into midge flies which may result
in a minor indoor bug infestation. However, one consolation-they don't bite.

Daphnia Delicacy - This very common plankton frequently exhibits dense blooms
in fishless ponds usually in the spring, and also, erratically in lakes during
the summer. Massive quantities can be easily collected with a fine meshed dip
net or seined and frozen as an excellent fish food. Small amounts can be kept
alive, but keep the water cool and well aerated. Often, other tasty treats
such as fairy shrimp and glassworms are present and make a splendid mix which
your fish will die for! Daphnia does have a hard shell (exoskeleton) which may
turn off some finicky fish initially, but after a week on the new menu, most
hold outs develop more than just a casual appetite for these scrumptious

A New Brine Shrimp On The Block - For decades, the Editor has used frozen
brine shrimp which my fish dined on happily, but always clouded the aquarium
water. Now there is an almost crystal clear alternative which is harvested
from the plains of Saskatchewan and packaged by Fish King of Chicago. It's
definitely worth a try!

I'll Have Mine Decapped - Sounds like a coffee commercial, but decapsulated
brine shrimp eggs really do provide an excellent food for fish fry. I received
a sample from a private hatchery for feeding one week old blue suckers and
they just can't get enough of it. The eggs come in one pound cans and are
normally sold by the case, but the distributor will sell single cans on a
prepayment basis plus postage. For more information contact: INVE Aquaculture
Inc., P.O. Box 136, 598 W. Clark St., Grantsville, UT 84029 Phone: (801)
884-3406/Fax (801) 884-6492. (Item #1SFPT5)

Gravel Washers or shotguns have been around for some time and are an
incredible and valuable tool used in aquarium maintenance. Typically this
simple device consists of a siphon tube connected to wider funnel intake which
vacuums the gravel. Aquariums should have about a 25% water change per month
and the gravel washer accomplishes both tasks at once. Thrust the funnel deep
into the gravel and slowly pull up. The siphon action removes only the finer,
lighter waste particulates and leaves the gravel behind. Extremely plugged
gravel beds may require two passes and once a year, remove all plants and
rocks to vacuum the entire bottom in conjunction with about a 75% water
change. If this schedule is followed and the fish are not overfed or
overcrowded, the aquarium should never have to be torn down and cleaned ever
again. However, the Editor must admit at being somewhat negligent in this
department and still goes through the age old ritual about once a year.

Algae Management - Probably the best practice is controlling the amount and
duration of light entering the aquarium. When setting up for the first time,
select a room which does not receive direct sunlight (e.g., south exposures).
Light fixtures should provide sufficient light to see into the aquarium, but
avoid wattage overkill - more is not always better. Duration should ideally be
around six hours a day and an electric timer is an excellent and inexpensive
convenience. Another option is live, rooted plants which compete for the same
nutrients as algae and when established usually gain the edge while adding a
nice natural touch. One final must is a scraper that won't scratch the glass
and has no detergents. The best and cheapest is a green 3M scrub pad available
at grocery stores. However, when working in or near the bottom, watch out for
gravel sandwiched between the glass and the pad. On thick pastures, a single-
edge razor blade provides a close shave, but one strip at a time and avoid
slashing the glass.

Drugs, Chemicals, And More - Professional Sporting Goods, Inc. (Formerly
Jungle Laboratories) has everything under the sun for keeping fish healthy and
frisky. Some of the items advertised in their Bait Products Catalog include
Baitsaver, Bubble Tabs, Catch and Release, Ace Ammonia Chloramine Eliminator,
Bait Food, Bait Salt, Foam Kill, Hypno (fish calmer), Net Soak, and Parasite
Guard. The catalog also provides a Bait Problem Solver Chart that describes
the problem, appearance, cause, proper action, and applicable notes. Only
dealer quantities are listed, but when it was still Jungle, smaller orders
were also graciously accepted. Catalogs can be requested from (800) 835-2248
and don't forget to check out the introductory offer coupons on the last page.

Pills, Potions, And Powders - The Fishy Farmacy carries scores of mail order
medications to keep your fish happy and healthy. Catalogs are available from
(800) 423-2035 or CA callers: (800) 32-FISHY.

DC Power - Air pumps that run on batteries can be very useful on collecting
trips and a life saver for aquariums in the event of a power failure.
Unfortunately, most pumps available from bait stores last only a few hours and
the airline constantly falls off the poorly designed nipple. However, there
are two that fit the bill. Hagen (ART.#A-790) and Bubbles air pumps run on D
batteries which last for days. The Hagen pump costs about $10 and is available
through pet stores and the Bubbles (Item 363-223) is $20 and can be mail
ordered from Bass Pro Shops (800) 227-7776. Before you buy, request a catalog
and check out the larger DC air pumps and submersible powerheads that will run
off 12 volt batteries.

Fish And Lake Management Supplies - The Aquacenter carries a wide array of
mostly aquaculture merchandise which includes pools and tanks, water and air
pumps, info videos, chemicals, feed and feeders, filters, chillers, heaters,
water chemistry/quality meters, and nets. Catalogs are available from (800)

Shipping Fish 101 - The old guard must plead guilty to elitism from time to
time in not providing enough information on the basics, but we definitely got
the message and will try to make amends. The following pointers have worked
well for this trader which includes one episode where the box was lost for 9
days and miraculously still had 100 percent survival. First, find a sturdy and
insulated box such as the type tropical fish stores use. Sometimes there is a
charge and sometimes you can find perfectly good ones dumpster diving. Bag
size is a personal preference, but I use either 2 half box bags laid
horizontal or one box liner. Pour just enough clean aquarium water into the
bag that will allow the fish to swim upright or with a slight list and also
able to turn around. Never over crowd (4 - 8 minnow size fish per half box
bag). It's optional, but some swear by additives such as Start Right or
ammonia chips. If available, fill the bag with oxygen (try bait stores). Seal
it with heavy duty rubber bands and insert the bag upside down into another
bag and reseal again. When sending only one bag, use some type of packing
material to prevent rolling. Place a duplicate mailing label inside just in
case and seal the box with nylon strapping tape. Cross out old addresses with
a magic marker. In the summer, postpone shipment when current or forecasted
temperatures exceed about 90 degrees (F) or below 32 in the winter. In
borderline temps, use over night services, but spring and fall shipments can
usually go first class priority. Good luck and enjoy.

An Electrifying Technique For Fish Photography - The March 1989 Tropical Fish
Hobbyist reported on this novel idea for filming natives which immobilizes the
subject and also keeps fins straight and erect. However, the author first
offers several suggestions which help in achieving picture perfect results. 

Esthetically landscape the aquarium (20-40 gallons) with a variety of
backgrounds that contrast the subject's characteristics (e.g., dark fish:
light background vs. transparent fins: dark back-ground). 
Aquarium glass should be free of scratches and wipe off air bubbles. 
Use a high photographic quality glass sheet which is thrust into the gravel
lengthwise across the front of the aquarium. This will reduce glare and
reflections, and also, confines and positions the subject broadside. The
electricity is delivered to the aquarium via two 14 gauge insulated copper
wires which are inserted 8 inches deep at opposite ends of the aquarium with
the last 4 inches stripped of insulation. The recommended optimum photographic
current was 32 volts of AC equipped with a rheostat (available from electrical
outlet stores) which permits for customized settings dependent on each fish's
body size and shape. A single-lens reflex camera on a tripod is positioned in
front of the aquarium with three electronic flashes placed on each side and
directly overhead. The correct aperture (f-stop) requires some trial an error,
but should not take more than one roll of film. The article also showcased 20
excellent color photos of native fish using this method. Last and most
important, the author emphasized safety. Remember this requires dealing with
electricity and water which can definitely not be a healthy or harmless
combination when improperly used. Editor's Note: The author did not mention,
but obviously used extension tubes, close-up filters, or a macro-lens on the
smaller fish subjects to achieve the desired magnification. 

Mail Order Collecting Gear - Ever have trouble finding a local, year round
source for gear and accessories. Mail order may be the solution and Nylon Net
and Memphis Net and Twine are perhaps two of the best sources. Besides the
routine, items include nets of all designs (gill, trammel, hoop, trawl, cast,
lift, and bait), minnow traps including a collapsible model, chemicals for
transporting fish, AC and DC aerators, Commercial fishing How to Books, and
much, much more. Free catalogs can be ordered from Nylon Net at (800) 238-7529
and Memphis Net at (800) 236-6380.

More Mail Order Catalogs - Come to expect them as a sign of spring like seed
catalogs. There are quite a few out there and all vary in items which apply to
collecting accessories. Get on their mailing lists and shop around. However,
on the last three, request the Spring and Summer catalogs because Fall and
Winter get a little sparse on fishing accessories. (1) Netcraft (800)
638-2723. (2) Bass Pro Shops (800) 227-7776. (3) Cabela's (800) 237-4444. (4)
Gander Mountain (800) 558-9410.

Collecting Gear Summary - There are generally two categories or types of
collecting gear - active and passive. Active gears pursue fish and include
seines, kick (dip) nets, cast nets, and trawl nets. Passive gears are usually
set from a few hours to overnight and fish are attracted or guided into the
gear where they become trapped. Examples include minnow traps, umbrella (drop)
nets, gill nets, trammel nets, fyke nets, and set lines. Laws vary from state
to state, but many gears can be used with simply an angling license. Larger
gears are also an option, but may require a commercial fishing or bait
dealer's license. One final alternative to consider is applying for a special
use permit for scientific or educational purposes. However, permits are
generally granted with stipulations such as prior notification of fisheries
managers and conservation officers, and always a year end report. 

Seines are probably the most widely used type of collecting gear and are
extremely effective on many fishes when properly used. Seines come in various
lengths, depths, mesh sizes, and fabrics. The Editor's personal preferences
include nylon seines, 10-15 long, 4 feet deep, and a mesh size of one eighth
to three sixteenth inch. Larger seines become unmanageable in swift currents,
and smaller meshes clog with algae and debris, while larger meshes either lose
or gill net fish. In lakes and slow streams, seines can be dragged in any
direction, but swift currents work best going downstream. Tips to remember
include keeping the lead line in contact with the lake or streambed as much as
possible to prevent escape. Poles tied to each end make this easier and also
work as convenient handles. It's also better to keep the seine loose and allow
a small bag to form in the middle instead of maintaining a tightly, stretched
tennis net. A typical seine haul runs parallel to shore until the inside
person slows or stops and the outside person pivots around for a final drive
into shore. If there is insufficient room to beach the seine, get as close as
possible and slowly drag the lead line in and funnel catch into the middle
before lifting. If underwater debris near shore foils any attempt at landing
the seine, try a rapid midwater lift, but scoop forward and up with the lead
line. In riffles and rapids, stretch the seine out and hold it stationary.
Remember, there should be no gaps between the lead line and streambed.
Preferably with 3 or more people, begin kicking rocks about 10 feet upstream
and work down to net's edge. The seine holders can assist with kicking by
holding their pole in one hand, pivoting around it, and march in a row down
into the seine. Then quickly pivot back and lift seine while simultaneously
scooping forward with the lead line. Seines can also be hauled solo, but
require some more preparation. Stake one pole into the shore and stretch seine
along water's edge. Then, slowly arc 180 degrees around stake and beach the
seine. Push seines also have a place especially in pools of small streams
where my preference is a four footer with poles tied to each end. Finally,
like drag seines, push seines also work well in riffles, but require one
holder and one kicker to get the job done right.

Cast Nets are circular nets which are thrown over a passing school of fish or
into deep holes. When the ring of sinkers hits the bottom, a slip cord bags
any fish trapped under the descending umbrella. Cast nets work very well in
scour holes below dams and falls where water is too deep to seine. However,
you only get one chance per site to ambush fish so practice up before hitting
the prime habitat. When-ever possible, cast from a vantage point such as a
dock, bridge, or boat. Make sure the sinkers are not tangled and remove
watches and rings. Tie the slip cord around one wrist, and with the other arm,
reach up inside the skirt and drape one lower edge (about 6-10 inches of
fabric) over an extended hand up to the shoulder. With the waist, wind up and
pitch the net like a giant frisbee. Don't go for distance just circular
coverage. Plastic net throwers are also available and help on both distance
and coverage. The Editor's personal preferences include small nets (3.5 ft.
radius) made of nylon multifilament (not monofilament) material. 

Kick Nets are the Editor's collecting gear of choice and actually are merely
landing nets which have a much finer mesh (one eighth to three sixteenth
inch). Some sporting goods stores and mail order catalogs carry smelt, shad,
and minnow dip nets which work just fine. Otherwise, you'd better learn how to
sew! Regulations vary from state to state, but the only restriction in
Minnesota is in the spring to protect spawning game fish from demonic dippers.
Kick nets work best in streams on darters and other riffle species. Place the
hoop firmly on the streambed and assure there are no gaps where fish can
escape. Kick rocks about two feet upstream of net and work down to net's edge
and scoop up. Kicking stream banks, rocks, and woody debris are much more
productive than working barren expanses void of structure and cover. Kick nets
also work well in small stream pools and lakes, but require seeing your quarry
and polarized sunglasses really help even on cloudy days. In pools, start at
the lower riffle and slowly walk upstream with the net stretched out toward
one bank which herds fish against the upper riffle. Look for a rocky chute or
deepest part of the stream that will serve as a natural funnel and place net
at the downstream end. Hold the net in one hand and quickly charge the school
in a circular sweep down into the net. In lakes, kick submerged weed beds,
cattail fringes, boulders, and logs. A spear and scoop technique can be just
as effective, but works best with telescoping handles. Schools of minnows will
occasionally watch you from just a few feet away. Aim beneath the densest part
of the school and plunge the net like a pool cue at sharp angle and scoop up.
Kick nets also work on invertebrates (bugs), crayfish, tadpoles, and

Minnow Traps come in several designs, but the Editor prefers metal, double
funnels, and quarter inch mesh or smaller. Small, marker buoys help in finding
traps the next day and can be easily made from Styrofoam and about six feet of
nylon line. Bait traps with bread, dog and cat food, beef heart, or even
chunks of ivory soap bars. However, some species such as brook sticklebacks
and northern and southern redbelly dace find barren traps irresistible. Place
traps in slow, slackwater areas such as eddies and pools and better yet next
to logs, root wads, boulders and overhanging bank vegetation. Whenever
possible, conceal the float to prevent anyone from rescuing what may appear to
be an abandoned minnow trap. In the right habitats, an overnight set can catch
400-600 fish per trap. Generally, small streams, ponds, and swamps are far
more productive than large rivers and lakes. Finally, daily limits are often
generous (hundreds of minnows per day) and laws typically require an angling
license, owner's name and address on the trap, and be checked every 24 to 48

Nocturnal Nettings - Many fishes, especially in lakes and large rivers, are
much more active at night than in the day. Members of the catfish family
(e.g., madtoms) are probably the best known species, but several darters,
minnows, and other small fishes either move out from cover or into shallower
water beginning around dusk. Seines work best in open water and kick nets in
riffles. However, reconnaissance is a must and sites should be examined during
the day for submerged logs, boulders, and drop offs. If there are any of the
latter, wear a life jacket! Headlamps are also extremely handy and available
from sporting goods stores and mail order catalogs. Finally, mosquitoes often
descend in hideous hordes right around twilight. Either use repellent or try
it again a couple of hours later. The obnoxious menace will frequently and
mysteriously drop to zero.

Crystal Darter Collecting Techniques - Ray Katula (Genoa, WI) and the Editor
spent an interesting day on the Red Cedar River near Durand, WI in August
1995. With only a 25 foot seine, we caught three crystal darters (Ammocrypta
asprella) in about 20 minutes of effort. That is after we identified their
preferred habitat which consisted of runs with moderate current over loose
gravel in about 3.5 feet of water. We only collected crystals while seining
downstream at almost a dead run. Due to logs along the banks, seines were
rarely beached, but scooped up in midwater. Dr. Jay Hatch (University of
Minnesota) has been studying crystal darters in the larger and deeper
Mississippi River where most of his collections have also been made with
seines in a downstr