[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
No Subject
<HTML><PRE>
SUCCESSFULLY SPAWNING AND RAISING
THE GREEN SUNFISH (Lepomis cyanellus)
By Peter R. Rollo,
prollo at juno_com
In Southeastern Pennsylvania, spawning begins in early
June or when the water temperature approaches 70 F. In
the summer of 1992, while on a fishing trip in mid
June, I was able to observe Bluegill, Pumpkinseed, and
Redbreast Sunfish performing their spawning ritual. The
spawning species were verified when I caught a few of
the fish on my fishing rod. I was not able to observe
the nest building process, as the males had already
completed this task and were guarding their nests from
all intruders. The nests were constructed in water less
than 12 inches deep and closely spaced (the edge of the
nests touching adjacent nests). In the spawning ritual,
females approach the males and begin circling each
other with fins fully extended. After a short time the
pair stops circling and the female tilts her body to
a 45 angle. The eggs are released and
simultaneously fertilized by the male. The females rarely
spawn with only one male. They generally move on to other
males to complete spawning while the males remain on their
nests to guard the eggs.
Throughout the summer of 1992 I collected several green
sunfish for my aquarium. Some had to be returned to their
original body of water due to conflicts with the other
sunfish already in the tank. Eventually I was able to
collect two individuals of the same size that got along
with minimal fighting. A third juvenile green sunfish and
brown bullhead catfish, about the same size of the
others, found in a local pet shop were also added.
Amazingly, all four fish got along. Being juveniles I had
no way of accurately sexing the sunfish, but I hoped that I
had captured a pair. In Pennsylvania, my understanding is
that Sunfish can be legally collected with a fishing rod
and valid fishing license. Instead of taking them home
to fillet, they accidently found their way into my
aquarium. As long as the fish are cleanly hooked in the
mouth, they suffer no ill effects and are feeding by the
first or second day.
I maintained the fish all summer in a "community" style 20
gallon high aquarium in my outdoor shed. The shed is
equipped with a thermostatically controlled exhaust fan to
prevent heat buildups.
The average summer temperature of the aquarium water was
about 80
F with a pH of 7.0. No other attempts to alter water
chemistry were made. Filtration was provided by a Fluval 3
internal power filter connected to a spray bar and a Penn-
Plax Clear-Free corner filter (Model CF-1). Drift wood,
small rocks, a flower pot turned on its side and about
an inch and a half of gravel were provided along with
the aquatic plants Vallisneria, Ludwigia, Sagittaria,
Bacopa and Elodea (Anacharis). Anacharis grows wild in
the waters where I caught the sunfish. The plants
do moderately well in the summer, but really thrive and grow
quickly in the winter when the water temperature is below
50 F. The tank is enclosed in a plywood box with removable
lid insulated with styrofoam. An air space of about 4
inches surrounds the sides and top of the tank. Minimal
heating is provided using a voltage regulator connected to
heat tape. The heat given off by the heat tape warms the
air space. This warm air is pumped into the tank by the
air pump and effectively prevents freezing or major drops in
temperature. The heat is manually controlled and used
only when excessively cold.
In the summer the sunfish are fed moderately heavy every
second or third day and in the winter they are fed sparingly
every three or four days whenever the water temperature
rises above 50 F. Below 50 F the food in their stomachs
digests so slowing that it can actually spoil before
digestion is complete, killing the fish. Besides, I
am trying to recreate their natural environment, and
minimal feedings in the winter is part of it.
The foods offered include fresh frozen mummichogs, grass
shrimp
and Atlantic silversides, grasshoppers, crickets,
nightcrawlers,
chicken heart, freeze dried krill, freeze dried daphnia,
freeze
dried shrimp, dry cichlid pellets and any other insect I
can
catch. The Mummichogs, grass shrimp and Atlantic silversides
were
caught with a minnow trap and net while vacationing at the
beach. These foods are their staple winter diet when the
regular live foods are not available.
There are no provisions to chill the water in the summer.
The fish endure an average summer temperature of 80 F
and an average winter temperature of about 40 F. Forty
percent water changes are generally made once a week
in the spring and fall but usually every few days in the
summer. Twenty-five percent water changes are made about
once a month in the winter (when water temperatures are
consistently below 55 F). Don't be lax with water
changes. These fish have big appetites and produce large
amounts of waste. It is extremely important that all water
added to the aquarium during water changes be the same
temperature as the water in the aquarium or temperature
shock to the fish will result.
This group of fish were overwintered as naturally as
possible in the hope that they will be properly cold
conditioned and ready to spawn in the spring. As soon
as the weather began to warm another 20 gallon high
spawning tank was set up in the shed. Except for the
gravel and sponge filter the tank was kept bare. A
chiller unit was utilized to maintain an optimum
temperature (70 F) for spawning and raising fry during the
hot summer months. In April, 1993 as the water temperature
slowly increased two of the sunfish began to swell with
eggs but the remaining sunfish did not exhibit any male
behavior or female egg development. By the end of June,
1993 nothing had changed and I decided to release that
fish to its native waters and attempt to capture another
fish in the hope I could find a male. Fishing was poor the
day I went out and was only able to catch one beautifully
colored juvenile green sunfish. I was hoping its
bright coloration meant it was a male because none of the
other fish I captured showed such color. As the fish
matured (he more than doubled his size in three months) I
realized it was a male and hoped it could be induced to
build a nest and spawn.
October approached and by this time I was becoming
frustrated because I had already put a year and a half of
effort and alot of money into this experiment and did not
want to wait till next spring to see if spawning would
occur. November began and no interest to spawn was
shown by the fish. The beginning of November was
warmer than normal and the temperature in the community
sunfish tank spiked about 8 F in a short time period.
The male sunfish began excavating gravel in all areas of
the
community tank. When male sunfish are ready to spawn
their
colors intensify, they excavate a nest in the gravel and
await a
receptive female. Even though the male sunfish appeared
to be
excavating a nest and I noted his colors were brighter
than
normal I paid no attention to what he was up to. On
November 15,
1993 I checked on them at 10 PM and every thing seemed
as it
should. However, when I went out to check on them at 10
AM on
November 16, the male was stationed in the middle of the
nest and had all the other fish pinned in the opposite
corner of the tank and would not let any of them out. I
thought this odd behavior but I still had not realized
what had occurred. I looked at the larger female who the
night before was loaded with eggs and saw that she was as
thin as a rail. When I quickly looked back at the male I
noticed eggs, hundreds of eggs. They had spawned over night
and the male was protecting the eggs. The fertilized eggs
are adhesive, perfectly round, colorless and approximately
1/16 of an inch in diameter.
I quickly removed all the fish except the male and put
them in
the spawning tank. The spawning female was a bit ragged
with
torn fins and the other fish were all in good shape. The
fluval
filter and spray bar were removed and replaced with an air
driven
sponge filter to ensure that none of the eggs or fry
would be
sucked into the filter. Air flow was high enough to
cause a
light current in the aquarium. The current prevents any
harmful
material from settling on the eggs and wigglers. A 25%
water
change was also made. The community tank was not intended
for
spawning and was in need of a change anyway.
On November 17 I noticed that any eggs kicked up by the male
were
quickly eaten so I took him out and put him in with the
other fish. I now anxiously waited for the eggs to
hatch. No chemicals were added for egg protection.
Clean, well filtered and aerated water is sufficient.
Based on my reference books sunfish eggs hatch in 3-5
days at 80 F and quicker at cooler temperatures. On
November 19 the eggs finally hatched. It only took 3
days at a water temperature of 65 F and a pH of 7.0.
There were no apparent problems with bacterial or
fungal
infestations of the eggs as evidenced the large number of
eggs
that hatched. With a little care and the heat tape turned
way up
I was able to maintain the tank to within plus or minus 2 F
of 65
F to ensure proper incubation of the eggs and development
of the
wigglers into fry. The wigglers were entirely clear, no
visible
markings could be seen. Within 24 hours (November 20) eye
spots
became apparent and the wigglers started to take the form of
fish 24 hours after that (November 21). Fifteen to
twenty-five percent water changes are made every day and so
far all is well.
With regard to how long it takes for the wigglers to become
free
swimming my references estimate about one week. On November
25 I
noticed a few fry making their first attempts at
swimming on their own. I offered a very small quantity of
brine shrimp but none were accepted. No further
offerings were made until the 27th. This was the eighth
day since hatching and dozens were free swimming. I
again offered a very small quantity of brine shrimp and
for the first time the fry began feeding. By the ninth
day all were free swimming and brine shrimp feedings began
twice a day, once in the morning and once in the evening.
The feedings require that the aeration and filtration be
turned down to a minimum. This prevents the shrimp from
being sucked into the filtration system and because
the fry are somewhat uncoordinated they cannot
successfully capture the moving shrimp in moving water.
With still water it takes them several attempts before they
can capture the shrimp. This will quickly pass as the
fish grow and become proficient swimmers. It is easy to
determine which fry are feeding. Since their bodies are
still transparent, consumed shrimp give the fry orange
bellies.
Two months have passed and the majority of the fry are now
¬ inch or larger. The remaining fry number about one
to two hundred. The fry that were unable to swim properly
and/or feed consistently quickly died. At first several
fry were dying daily, but now virtually none are dying on
a regular basis. I figured I lost about 100 fry to
what I will call natural selection. At any rate, their
survival is by far better than it would be in their
natural habitat. Due to limited space, I am experiencing
cannibalism of the smaller fry by the larger fry because
I am unable to provide the tanks necessary to separate out
the larger fry as needed. The fry are still mostly
dependent on brine shrimp, but will be weaned off the
shrimp as soon as they are large enough and can be
persuaded to accept other foods. Even after two months most
of the fry still do not resemble their parents, i.e. their
pelvic fins are not yet visible (dorsal and anal fins are
faintly visible) and their bodies are still
substantially transparent. I will consider them juveniles
when their body shape and coloration resembles adult
sunfish. This is expected to occur in the next one to two
months. This experience has been very rewarding and
helpful in understanding the life cycle of the Green
Sunfish as well as Sunfish in general. I look forward to
spring when I hope to experience another spawning of the
Green Sunfish.
</PRE></HTML>
Robert Rice
Help Preserve our Aquatic Heritage join the NFC
email us at NFC at actwin_com or Sunfishtalk at listbot_com
website http://nativefish.interspeed.net/