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Pass it on....
SUCCESSFULLY SPAWNING AND RAISING
THE GREEN SUNFISH (Lepomis cyanellus)
By Peter R. Rollo,
2308 Cedar Lane,
Secane Pa,
19018
1-610-543-1660
North American Native Fishes Assossiation
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 1/4
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.