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Determining whether angelfish has better defense mechanism and high rate of activity as compared to tetra fish when subjected to different stimuli


            Most animals sleep, hunt, hide, fight, or swim erratically as a means of survival. In the case of fish, the manner in which they end up surviving in water environments is what has the ability of determining the rate at which they grow, swim, hunt, hide, sleep, or escape from predators.  The reason for that is because those are the main adaptations that have been realized to impact the survival of various fish species. Despite that, regardless of the means that fish species utilizes in fostering their survival mechanisms, each one of them is absolutely adapted differently (Iwaya-Inoue et al., 2018). The period of metabolism, defense, and activity, for instance, is also determined by the manner in which the fish species feed, conserve energy, as well as restore its body mass.

            The collected information regarding the impact of physical environment, feeding ingredients, as well as other factors affecting sleep, defense, growth, and swimming on fish are some of the important factors for that have to be taken into consideration. However, although the existing literatures suggest that such mechanism any fish species is dependent on the surrounding stimuli subjected to, it is important to understand the performance or adaptations of each fish species in such an environment (Planas et al., 2017). The essence of this research is to determine the defense mechanisms and the activity rate of angelfish and tetra fish when subjected to similar aquariums.


            Determining whether angelfish has better defense mechanism and high rate of activity as compared to tetra fish when subjected to different stimuli


The null hypothesis for this experiment indicates that angelfish has a higher rate of activity and defense mechanism as compared to tetra fish


5 angel fish chosen randomly and placed in a bucket filled with fresh water

5 tetra fish chosen randomly and placed in a bucket filled with fresh water

Two aquariums of about 100cm by 100cm and each built with different habitats comprising of wood, stones, or plants.

A thermometer, a stick, and ice cubes of preferable sizes

Food especially small phytoplankton and zooplanktons


Introduce the 5 angelfish into one of the aquariums prepared and let them to maneuver freely.

Then place the 5 tetra fish into the other aquariums and give the time to maneuver freely.

Using a stick, try to disturb the angel fish contained in separate habitats of their aquarium and note how faster they swim before coming to rest. Introduce both the phytoplankton and zooplanktons into the aquarium and note their reactions or the feeding characteristics of the fish.

Next, place the ice cubes in the aquarium, record its temperature, and then note the activity of the fish. Conduct the experiment for two hours in the morning, then two hours in the afternoon, for one hour in the evening, and finally for one hour in the midnight. The same procedure should take into account determining the time taken for the fish to sleep both at daytime and nighttime.

Perform the same experiment on the aquarium containing the 5 tetra fish in each habitat.


            For the aquarium containing angelfish, it was found out that they liked occupied same habitat regardless of their shape and size. On introducing both phytoplankton and zooplanktons to the aquarium, it was found out that the angelfish were more attracted to zooplanktons as compared to phytoplankton. Although they are faster swimmers once disturbed, their activeness decreases at nighttime as compared to daytime. Ideally, they did not take a lot of time to sleep whether during the day or at night. Feeding also took place both on the surface and the bottom of the water within their aquarium. Moreover, introducing ice cubes into the aquarium made the fish to be relatively inactive. 

            On the other hand, for the aquarium containing tetra fish it was found out that each one of them liked staying in groups regardless of their size. They consumed both phytoplankton and zooplanktons. At nighttime, they still take time to feed hence limiting their sleep time as well as increasing their activeness. Once the water was disturbed, the smaller tetra fish tended to cling to larger ones for defense. Likewise, they liked feeding closer to the surface of the water than on the bottom. Introducing ice cubes into the aquarium made the fish to be relatively inactive. 








                        A graph showing the activity rate for angelfish and tetra fish against time






           Activity    30                                                                    

             Rate        25

                           20                                                                                          Curve A

                            15                                                                                          Curve B



                                                                                                                                               X- Axis

                                          1       2        3      4        5     6       7       8       9       10

                                                                    Time (hours)                                                                                                                                                                                                                                           


Curve A= activity rate for angel fish

Curve B= activity rate for tetra fish


            From the above experiment, it was found out that angelfish always move in groups as one of their structured aggregations. Accordingly, relatively larger fish had the ability of leading others as well as directing them to food. They actively change their shoal structure whenever they encounter food. Regardless of that, there was a significant variability in terms of feeding habits which is absolutely based on individual fish size and their aggressiveness. As much as the activity of each angelfish is concerned, large angelfish end up consuming a large amount of food which in return increases their activity or metabolism. On the other hand, the distribution of each fish in the aquarium is dictated by their size, shape, and aggressiveness towards food. Smaller angelfish ultimately benefit through following larger ones. Although angelfish are apex predators, juvenile cods prefer different swimming and feeding grounds (Lass, 2012). This implies that angelfish are carnivorous hence consuming a lot of food so enable them remain healthy and reach optimum size.

             As much as defense mechanisms are concerned, the angelfish move in shoals so as to protect the young ones from predators. Maintaining balance and shielding each other assist in supporting each one of them from danger. Likewise, their sleep patterns keeps on varying taking into account the condition or the danger they are subjected to. Ideally, it was noted that they only sleep when the light is turned off. In the process of disturbing them, it is evident that juvenile angelfish are extremely fearful and end up hiding in any of the habitat present in groups (Sexton, 2009).

            In the aquarium containing 5 tetra fish, it was found out that all of them remained to be more active at daytime as compared to nighttime. Daytime feeding is one of the factors that improve the activity of the tetra fish. As a result of daytime competition, they equally feed at night as a way of obtaining extra nutrients. Likewise, within the plant habitat, it was a clear indication that tetra fish is an omnivore fish pronominally feeding on aquatic plants and planktons. Tetra fish always feeds on shallow waters to avoid harmful gases and temperature fluctuations. It is this strategy that has the potential of maintaining the physiology of the fish hence maintaining their activity (Hargrove & Hargrove, 2011). 

            Tetra fish establish social chain of command in which larger ones, especially male have a more precedence for food. In order to protect the young ones, large takes the responsibility of protecting them. The majority of them live like a family consisting of one male and female in each colony or habitat. This is a clear indication of the fact that tetra fish have to leave in groups to avoid them from being stressed up if left alone (Hargrove & Hargrove, 2011). For both of these fish species, the decrease in water temperature was noted to have the ability of decreasing their body activity.









Hargrove, M., & Hargrove, M. (2011). Freshwater Aquariums For Dummies. Hoboken: John Wiley & Sons, Inc.

In Iwaya-Inoue, M., In Sakurai, M., & In Uemura, M. (2018). Survival strategies in extreme cold and desiccation: Adaptation mechanisms and their applications.

Lass, D. A. (2012). Angelfish: Understanding and Keeping Angelfish. Irvine: I5 Publishing.

Planas, J. V., Palstra, A. P., & Magnoni, L. J. (2017). Physiological Adaptations to Swimming in Fish. Place of publication not identified: Frontiers Media SA.

Sexton, C. A. (2009). Angelfish. Minneapolis, MN: Bellwether Media.

1351 Words  4 Pages
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