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view/download model file: RevisedFishSpawnModel.nlogo

WHAT IS IT?

A simulation of fish that swim, eat, grow, reproduce, excrete waste and die.


HOW IT WORKS

Two breeds of fish, male and female. Periodically, some amount of food is added to the fish tank.
As fish swim, they use energy from food, represented as yellow patches, and age. As fish eat, they gain energy, grow to adulthood (and then stop growing) and add waste to water. Fish eat smaller fish Fish die if: energy runs out, they get too old, water quality is poor. Fish spawn according to a probability if boy fish and girl fish are near each other, are mature, have enough energy, and the water quality is good.
If food (the yellow patches) is not eaten, it rots and pollutes the water. The filter cleans waste and pollution from water depending on the flow of the filter Changing the water is a fast way to improve water quality.


HOW TO USE IT

Set the number of male and female fish that you would like to start with. Be sure to turn the filter to an amount adequate for the number of fish that you have. Set the amount of food they will get periodically.


THINGS TO NOTICE

Effects of variables on water quality and fish population. Relation between fish population and water quality. See relation between amount of food and population range. Watch the fry (baby fish) grow! Watch the monitors to see the causes of death.


THINGS TO TRY

Setting different ratio of male and female fish Changing probability of spawning Changing amounts of food Changing efficiency of filter


EXTENDING THE MODEL

different types of fish that are more or less tolerant of variations in water quality size of tank monitoring when parameters are changed monitoring # water changes and when they occur plants nitrate variable fish activity and feeding as f (light) temperature pH dissolved oxygen and carbon dioxide disease transmission (e.g. Ich)
This section could give some ideas of things to add or change in the procedures tab to make the model more complicated, detailed, accurate, etc.


NETLOGO FEATURES

This section could point out any especially interesting or unusual features of NetLogo that the model makes use of, particularly in the Procedures tab. It might also point out places where workarounds were needed because of missing features.


RELATED MODELS

Nitrogencylce4


CREDITS AND REFERENCES

Cindy E. Hmelo-Silver Lei Liu 2004
Supported by the National Science Foundation