Behavioural
Processes,
13 (1986) 353-366
353
Elsevier THE
AGGRESSIVE
MULTICOLOR
BEHAVIOUR
(PISCES,
TERRITORIAL
BETWEEN
WITH
CICHLIDAE)
PSEUDOCRENILABRUS
UNLIMITED
OR
ONLY
VISUAL
CONTACT
Anders
Fern6
Department
of
1839, N-5011
(Accepted
15
Fisheries Bergen,
July
University
Biology,
of Bergen,
P.O. Box
Norway
1986)
ABSTRACT behaviour Fern6, A., 1987. The aggressive between Pseudocrenilabrus multicolor (Pisces, Cichlidae) with only visual contact. Behav. Processes, 13: 353-366.
territorial unlimited or
between development 0 f aggression territorial fish has experiments using visual been studied in laboratory only contact. In this comparisons of the aggressive behaviour study, were made between conditions of unlimited and only visual contact. Fighting cichlids in direct contact between two territorial decreased over time in a way similar to the aggressive activity between subjects permitted only visual contact. However, there were also important differences between the two conditions of contact. Low-intensity aggression with a distance between the subjects but was generally not occurred frequently in free interaction observed visual contact. presence of under conditions of The non-territorial fish increased the aggression between subjects with visual contact had no influence on fighting and but conversely decreased low-intensity between interacting aggression freely subjects. In addition, the low level of aggression after some time of unlimited contact was not transferred to a subsequent period of visual contact. indicate that the decrease of The results aggression visual contact is caused under conditions of by habituation, whereas in a interaction a balance is also free developed between attack and escape tendencies. The
mainly
Key words:
aggression,
habituation,
territory,
cichlid
fish
INTRODUCTION
The the
aggressive
expenditure
behaviour of an animal's
it to the risk of physical territorial
0376-6357/86/$03.50
animal
to
0 1986 Elsevier
in
defence
of a territory
time and energy
injury.
It is therefore
behave
in
Science
Publishers
such
involves
as well as exposing important
for
a way as to maximize
B.V. (Biomedical
Division)
a the
354
benefits
of the aggressive
behaviour
1964).
Especially
crucial
towards
territorial
conspecifics.
neighbours enemy
is generally
effect
In
(Wilson,
field
aggression
(Lowe-McConnel,
some
In
on
frequent (Fernald
and Hirata,
sites
(McKaye,
1977),
found
behind
waning and
been
has
observed result
between of
Peeke,
fish
has,
were
contact
sexual
breeding
fish has been where
fish
tube generally
wanes
(e.g.
Peeke
et.
and Peeke,
and Veno, to a
it has
another
cichlids
1972;
Peeke
et
1979),
al.,
1970) and
the
1976). The response
process
of
habituation
that the low level of aggression territorial
reinforcement
aggression however,
fish
and Molen,
found
between
rarely
establishment
is
often also
1969; Peeke
a and
physical
1980).
than one with
contact unlimited
may
interacting
investigated.
Siamese
conditions
between
freely
been
in the
(Cain and Baenninger,
without
situation
In the
fighting
of unlimited It was proposed be associated
contact
fish,
and only that
with
and consequently
a
less more
lead to habituation.
There
is
one
conditions
convict
the decrease contact.
laboratory
of unlimited
(Peeke and Peeke,
pairs
of
of dominance
differences
of
or
towards
glass
(see e.g. Assem
development
context
both
e.g.
1978)
territorial
1966; Peeke
interacting
habituation
territorial
easily
a for
been attributed
freely
resource,
is
1973).
The
visual
in
al.,
suggested
1984).
fish
experiments,
displayed
1969; Peeke
(e.g. Peeke,
has generally
it
between
or
et
1977; Holzberg,
and Colgan,
evident.
aggression
partition
of
observed
territorial
in laboratory
(e.g. Baenninger,
stickleback
Loiselle,
for a limited
of aggression
Gallagher
anabantoids
dear
a low level
often
1983; Grant
has been demonstrated
1971;
al.,
is
between
is often
the
glass This
to territorial
the so called
1977; Kodrick-Brown,
in more detail that
a
rapidly.
1968;
and competition
development
(Brown,
of aggression
in fish,
neighbours
aggression
mates
been
territoriality
1979; McKaye,
more
The
to strangers,
Albrecht,
et. al.,
investigated
the costs
regulation
The responsiveness
territorial
species
the
1975).
1956;
1978; Colgan,
and minimize
be
less than
studies
between
may
study
1982). The aggression
cichlids
with
unlimited
was less pronounced
Aggression
decreased
between
in stable
on
and conditions
the
freely but
of only
between
contact
than under
periods
territorial
fish visual
territorial
decreased conditions interacting
increased
with
over of
under contact pairs
time but visual
territorial transitions
355
bet.ween
stages
explained
as an interaction 1970,
There
in
fish. Aggression
of individuals
There
may,
as
is thus
and also
between
presence
or absence
natural
conditions.
on the aggressive was also
aggression situation
MATERIAL
found with
reducing
Groves
and
to
been
1985). between
of habituation
unlimited
visual
and
compare
the development
contact
and to examine
visual
of
information
influence
of a period a
subsequent
contact
was derived
fish which
in order
unlimited
also
species.
experiments
investigated
the
Recognition
may occur
The importance
and visual
in
has
1979; Myrberg,
of
territorial
changing
1979).
aggression
conditions
behaviour
between
that habituation fish.
different
from
during
and
that habituation
after
et. al.,
(e.g. Thresher,
of non-territorial
visual
e.g.
indicating
(Colgan
Additional
The
(see
increased
was undertaken
situation.
were
(habituation)
of aggression
evidence
of conclusions
free contact
contact
males
between
study
studies
sunfishes
in both unlimited
aggression transfer
field
territorial
differ
The present
processes
results
The
decremental
1983).
factor
some
interacting
however,
contact
a
for in damselfish
freely
between
regulation
the
between
of individual
appearance
claimed
some
also
cycle.
reproductive
and Peeke,
are
involved
is
the
(sensitization)
incremental Thompson,
in
may
vary
of unlimited period
of
to
from
was
transferred
a the
under contact visual
to see if the attenuation
contact
of the
to
of a
contact.
AND METHODS
cichlid Pseudocrenilabrus The small, mouth-brooding fish multicolor (Schoeller, formerly Haplochromis multicolor, Hilgendorf chosen for or Hemihaplochromis multicolor, see Wickler, 1963) was can be established in this study as several territories growth of middle-sized aquaria. The distribution, migration and this East African cichlid have been investigated in the field conducted (Welcomme, 1969), but only laboratory studies have been on the 1937; reproductive and territorial behaviour (Peters, Reinboth, establish 1956; Kuenzer, 1975; Mrowka, 1982). The males territories and are then generally brightly coloured with a bluish body and black eye-bars whereas females are more cryptically coloured. There is no pair-bondi_ng and after spawning the female leaves the male's territory with the fertilized eggs in her mouth. The fish in this study came from a population of P.multicolor originating from a local dealer and held The at the laboratory. territorial varied in length 5.7 cm males between 4.0 and (including the tail fin). The two subjects in each trial had a mean length difference of than 2 mm and were isolated from each less other at least three weeks prior to contact in the trial. Aquaria of 200 1 (100x50~40 cm) were used. The floor of the tanks was covered by sand and devoid of plants. A hide made by flower-pots and stones was placed at where the each end wall
356
subjects centered their territories. The aquaria were illuminated from above by three 15 W bulbs with a photoperiod from 11 a.m. to 11 p.m. The temperature was held at 25 '1.0" C. The fish were fed boiled liver or frozen fish flesh at the beginning and end of the light period. opaque partitions. Each aquarium was bisected with glass and One subject, along with four or five smaller conspecific males and aquarium and allowed to females, was placed in each half of the establish a territory. After five days the opaque partition was removed and, in Exp. 2, the glass partition was also removed. were made with only visual contact In Exp. 1, six trials fish and the opaque between the test subjects. Non-territorial time t partition were removed five min before (around 1 p.m.). Observations were made for one hr at time t and for 30 min at time 30 min at tf3 hrs during the first day of visual contact and for time t the following six days. In two trials, non-territorial fish placed in each half 0 f the (two males and two females) were aquarium after the observation on Day 7, and observations were made for 30 min at time t the following five days. Two of the trials were In Exp. 2, nine trials were conducted. one of the subjects lost his not included in the material as the trial was terminated. territory to the other subject before The subjects were first studied for a period with unlimited contact in the presence of non-territorial fish. (In trials l-3 this period lasted 14 days but as no change over time was found after the first five days in trials few days of contact., this period was set to 4-7, and only data from Days I-5 will be presented for all trials). time t and On Day 1, the partitions were removed five min before subjects were observed for one hr at time t and for 30 min at the were made for 30 min at time t + 3 hrs. On Days 2-5, observations time t. fish was then included in A period without non-territorial Exp. 2. The day after the period with non-territorial fish present, observations these fish were taken away five min before time t and were made for 30 min at time t for five days. periods without nonwith and The sequence of the territorial fish was thus not the same in Exp. 1 and Exp. 2. The reason for inital absence of non-territorial fish in Exp. 1 the usually include such was that visual contact experiments do not variable situation. In Exp. 2, fish because of the resulting absent,one subject pretests showed that if non-territorials were partition was removed. always lost his territory when the unlimited contact in Exp. 2, The day after the periods with the glass partition was reintroduced in the middle of the aquarium observed for seven days five min before time t and the subjects visual contact with the same procedure as in under conditions of Exp. 1. by one observer, Observations were made from behind a screen spoken into a tape recorder and later transcribed. The following behaviour patterns were recorded: Both unlimited
and only
visual stroke
contact
Tail-beat
A strong
with
the tail.
Low-intensity
subject or both subjects made a aggression One towards (approach), away distinct movement and away (approach--retreat, (retreat), or towards frontal in relati.on to the other subject. display) (The frontal displays were few and of short duration and were therefore included in low-intensity aggression). In free interaction, both subjects
351
generally at a distance from the territorial were border. Under conditions of visual contact, low-intensity aggression occurred when the was territorial border of one or both subjects not in contact with the glass partition. Sexual
behaviour Quivering often quivering motion.
Fluttering Specific
A swimming unlimited
to
movement
followed
along
by
the walls
swimming
with
of the aquarium
contact
Attack
A rapid
Fight
Various combinations of circling, tail-beating, attacks. lateral threat, mouth-fighting and The types 0 f behaviour in a fight were not recorded. A fight consisted often of long series of attacks and more than one reciprocated attack was defined as a fight.
Specific
to
only
thrust
visual
towards
another
fish.
contact
towards the glass partition A subject swam swimming up and down the glass partition oriented towards the other male and often bit at the glass panel.
Aggressive
these behaviour patterns by The frequency of performance of the subjects towards each other was recorded as well as the time Attacks and spent fighting, aggressive swimming and fluttering. sexual behaviour patterns towards non-territorial fish were also recorded. When the subjects did not exhibit any of the behaviour patterns described either swimming relatively above, they were were passively, digging or staying within the hide. The subjects brightly coloured during all the defined behaviour patterns except for fluttering. The size of a subject's territory was recorded to the nearest five cm in each observation as the distance from the end wall of the subjects during aquarium to the position bet.ween the low-intensity aggression (assuming that the territorial border ran parallel with the end walls). RESULTS Only
visual
The
contact
aggressive
swimming
displayed
by both
swimming
decreased
Processes,
13 (1986) 353-366
353
Elsevier THE
AGGRESSIVE
MULTICOLOR
BEHAVIOUR
(PISCES,
TERRITORIAL
BETWEEN
WITH
CICHLIDAE)
PSEUDOCRENILABRUS
UNLIMITED
OR
ONLY
VISUAL
CONTACT
Anders
Fern6
Department
of
1839, N-5011
(Accepted
15
Fisheries Bergen,
July
University
Biology,
of Bergen,
P.O. Box
Norway
1986)
ABSTRACT behaviour Fern6, A., 1987. The aggressive between Pseudocrenilabrus multicolor (Pisces, Cichlidae) with only visual contact. Behav. Processes, 13: 353-366.
territorial unlimited or
between development 0 f aggression territorial fish has experiments using visual been studied in laboratory only contact. In this comparisons of the aggressive behaviour study, were made between conditions of unlimited and only visual contact. Fighting cichlids in direct contact between two territorial decreased over time in a way similar to the aggressive activity between subjects permitted only visual contact. However, there were also important differences between the two conditions of contact. Low-intensity aggression with a distance between the subjects but was generally not occurred frequently in free interaction observed visual contact. presence of under conditions of The non-territorial fish increased the aggression between subjects with visual contact had no influence on fighting and but conversely decreased low-intensity between interacting aggression freely subjects. In addition, the low level of aggression after some time of unlimited contact was not transferred to a subsequent period of visual contact. indicate that the decrease of The results aggression visual contact is caused under conditions of by habituation, whereas in a interaction a balance is also free developed between attack and escape tendencies. The
mainly
Key words:
aggression,
habituation,
territory,
cichlid
fish
INTRODUCTION
The the
aggressive
expenditure
behaviour of an animal's
it to the risk of physical territorial
0376-6357/86/$03.50
animal
to
0 1986 Elsevier
in
defence
of a territory
time and energy
injury.
It is therefore
behave
in
Science
Publishers
such
involves
as well as exposing important
for
a way as to maximize
B.V. (Biomedical
Division)
a the
354
benefits
of the aggressive
behaviour
1964).
Especially
crucial
towards
territorial
conspecifics.
neighbours enemy
is generally
effect
In
(Wilson,
field
aggression
(Lowe-McConnel,
some
In
on
frequent (Fernald
and Hirata,
sites
(McKaye,
1977),
found
behind
waning and
been
has
observed result
between of
Peeke,
fish
has,
were
contact
sexual
breeding
fish has been where
fish
tube generally
wanes
(e.g.
Peeke
et.
and Peeke,
and Veno, to a
it has
another
cichlids
1972;
Peeke
et
1979),
al.,
1970) and
the
1976). The response
process
of
habituation
that the low level of aggression territorial
reinforcement
aggression however,
fish
and Molen,
found
between
rarely
establishment
is
often also
1969; Peeke
a and
physical
1980).
than one with
contact unlimited
may
interacting
investigated.
Siamese
conditions
between
freely
been
in the
(Cain and Baenninger,
without
situation
In the
fighting
of unlimited It was proposed be associated
contact
fish,
and only that
with
and consequently
a
less more
lead to habituation.
There
is
one
conditions
convict
the decrease contact.
laboratory
of unlimited
(Peeke and Peeke,
pairs
of
of dominance
differences
of
or
towards
glass
(see e.g. Assem
development
context
both
e.g.
1978)
territorial
1966; Peeke
interacting
habituation
territorial
easily
a for
been attributed
freely
resource,
is
1973).
The
visual
in
al.,
suggested
1984).
fish
experiments,
displayed
1969; Peeke
(e.g. Peeke,
has generally
it
between
or
et
1977; Holzberg,
and Colgan,
evident.
aggression
partition
of
observed
territorial
in laboratory
(e.g. Baenninger,
stickleback
Loiselle,
for a limited
of aggression
Gallagher
anabantoids
dear
a low level
often
1983; Grant
has been demonstrated
1971;
al.,
is
between
is often
the
glass This
to territorial
the so called
1977; Kodrick-Brown,
in more detail that
a
rapidly.
1968;
and competition
development
(Brown,
of aggression
in fish,
neighbours
aggression
mates
been
territoriality
1979; McKaye,
more
The
to strangers,
Albrecht,
et. al.,
investigated
the costs
regulation
The responsiveness
territorial
species
the
1975).
1956;
1978; Colgan,
and minimize
be
less than
studies
between
may
study
1982). The aggression
cichlids
with
unlimited
was less pronounced
Aggression
decreased
between
in stable
on
and conditions
the
freely but
of only
between
contact
than under
periods
territorial
fish visual
territorial
decreased conditions interacting
increased
with
over of
under contact pairs
time but visual
territorial transitions
355
bet.ween
stages
explained
as an interaction 1970,
There
in
fish. Aggression
of individuals
There
may,
as
is thus
and also
between
presence
or absence
natural
conditions.
on the aggressive was also
aggression situation
MATERIAL
found with
reducing
Groves
and
to
been
1985). between
of habituation
unlimited
visual
and
compare
the development
contact
and to examine
visual
of
information
influence
of a period a
subsequent
contact
was derived
fish which
in order
unlimited
also
species.
experiments
investigated
the
Recognition
may occur
The importance
and visual
in
has
1979; Myrberg,
of
territorial
changing
1979).
aggression
conditions
behaviour
between
that habituation fish.
different
from
during
and
that habituation
after
et. al.,
(e.g. Thresher,
of non-territorial
visual
e.g.
indicating
(Colgan
Additional
The
(see
increased
was undertaken
situation.
were
(habituation)
of aggression
evidence
of conclusions
free contact
contact
males
between
study
studies
sunfishes
in both unlimited
aggression transfer
field
territorial
differ
The present
processes
results
The
decremental
1983).
factor
some
interacting
however,
contact
a
for in damselfish
freely
between
regulation
the
between
of individual
appearance
claimed
some
also
cycle.
reproductive
and Peeke,
are
involved
is
the
(sensitization)
incremental Thompson,
in
may
vary
of unlimited period
of
to
from
was
transferred
a the
under contact visual
to see if the attenuation
contact
of the
to
of a
contact.
AND METHODS
cichlid Pseudocrenilabrus The small, mouth-brooding fish multicolor (Schoeller, formerly Haplochromis multicolor, Hilgendorf chosen for or Hemihaplochromis multicolor, see Wickler, 1963) was can be established in this study as several territories growth of middle-sized aquaria. The distribution, migration and this East African cichlid have been investigated in the field conducted (Welcomme, 1969), but only laboratory studies have been on the 1937; reproductive and territorial behaviour (Peters, Reinboth, establish 1956; Kuenzer, 1975; Mrowka, 1982). The males territories and are then generally brightly coloured with a bluish body and black eye-bars whereas females are more cryptically coloured. There is no pair-bondi_ng and after spawning the female leaves the male's territory with the fertilized eggs in her mouth. The fish in this study came from a population of P.multicolor originating from a local dealer and held The at the laboratory. territorial varied in length 5.7 cm males between 4.0 and (including the tail fin). The two subjects in each trial had a mean length difference of than 2 mm and were isolated from each less other at least three weeks prior to contact in the trial. Aquaria of 200 1 (100x50~40 cm) were used. The floor of the tanks was covered by sand and devoid of plants. A hide made by flower-pots and stones was placed at where the each end wall
356
subjects centered their territories. The aquaria were illuminated from above by three 15 W bulbs with a photoperiod from 11 a.m. to 11 p.m. The temperature was held at 25 '1.0" C. The fish were fed boiled liver or frozen fish flesh at the beginning and end of the light period. opaque partitions. Each aquarium was bisected with glass and One subject, along with four or five smaller conspecific males and aquarium and allowed to females, was placed in each half of the establish a territory. After five days the opaque partition was removed and, in Exp. 2, the glass partition was also removed. were made with only visual contact In Exp. 1, six trials fish and the opaque between the test subjects. Non-territorial time t partition were removed five min before (around 1 p.m.). Observations were made for one hr at time t and for 30 min at time 30 min at tf3 hrs during the first day of visual contact and for time t the following six days. In two trials, non-territorial fish placed in each half 0 f the (two males and two females) were aquarium after the observation on Day 7, and observations were made for 30 min at time t the following five days. Two of the trials were In Exp. 2, nine trials were conducted. one of the subjects lost his not included in the material as the trial was terminated. territory to the other subject before The subjects were first studied for a period with unlimited contact in the presence of non-territorial fish. (In trials l-3 this period lasted 14 days but as no change over time was found after the first five days in trials few days of contact., this period was set to 4-7, and only data from Days I-5 will be presented for all trials). time t and On Day 1, the partitions were removed five min before subjects were observed for one hr at time t and for 30 min at the were made for 30 min at time t + 3 hrs. On Days 2-5, observations time t. fish was then included in A period without non-territorial Exp. 2. The day after the period with non-territorial fish present, observations these fish were taken away five min before time t and were made for 30 min at time t for five days. periods without nonwith and The sequence of the territorial fish was thus not the same in Exp. 1 and Exp. 2. The reason for inital absence of non-territorial fish in Exp. 1 the usually include such was that visual contact experiments do not variable situation. In Exp. 2, fish because of the resulting absent,one subject pretests showed that if non-territorials were partition was removed. always lost his territory when the unlimited contact in Exp. 2, The day after the periods with the glass partition was reintroduced in the middle of the aquarium observed for seven days five min before time t and the subjects visual contact with the same procedure as in under conditions of Exp. 1. by one observer, Observations were made from behind a screen spoken into a tape recorder and later transcribed. The following behaviour patterns were recorded: Both unlimited
and only
visual stroke
contact
Tail-beat
A strong
with
the tail.
Low-intensity
subject or both subjects made a aggression One towards (approach), away distinct movement and away (approach--retreat, (retreat), or towards frontal in relati.on to the other subject. display) (The frontal displays were few and of short duration and were therefore included in low-intensity aggression). In free interaction, both subjects
351
generally at a distance from the territorial were border. Under conditions of visual contact, low-intensity aggression occurred when the was territorial border of one or both subjects not in contact with the glass partition. Sexual
behaviour Quivering often quivering motion.
Fluttering Specific
A swimming unlimited
to
movement
followed
along
by
the walls
swimming
with
of the aquarium
contact
Attack
A rapid
Fight
Various combinations of circling, tail-beating, attacks. lateral threat, mouth-fighting and The types 0 f behaviour in a fight were not recorded. A fight consisted often of long series of attacks and more than one reciprocated attack was defined as a fight.
Specific
to
only
thrust
visual
towards
another
fish.
contact
towards the glass partition A subject swam swimming up and down the glass partition oriented towards the other male and often bit at the glass panel.
Aggressive
these behaviour patterns by The frequency of performance of the subjects towards each other was recorded as well as the time Attacks and spent fighting, aggressive swimming and fluttering. sexual behaviour patterns towards non-territorial fish were also recorded. When the subjects did not exhibit any of the behaviour patterns described either swimming relatively above, they were were passively, digging or staying within the hide. The subjects brightly coloured during all the defined behaviour patterns except for fluttering. The size of a subject's territory was recorded to the nearest five cm in each observation as the distance from the end wall of the subjects during aquarium to the position bet.ween the low-intensity aggression (assuming that the territorial border ran parallel with the end walls). RESULTS Only
visual
The
contact
aggressive
swimming
displayed
by both
swimming
decreased
