# Fish Experiment

Goldfish were one of the first fish ever to be kept as a domestic pet and still today, remain as one of the favorite household pets. Some goldfish have reached an age of 40 years old. Do you know what factors affect how a goldfish breathes? Catch your breath and start this investigation of Goldie, the goldfish.

### What is temperature?

Temperature is a measure of the average kinetic energy of the particles in a substance. In other words, temperature is the hotness or coldness of a substance. Temperature is measured in units of Celsius, Fahrenheit, or Kelvin.

### What is the dissolved oxygen concentration?

The concentration of dissolved oxygen (DO) is a measure of the amount of gaseous oxygen that is found in a liquid, such as water. Air typically has an oxygen concentration of about 210 cm3/liter, while a fresh water pond has an average DO concentration of about 8 cm3/liter. This means water only has about 3% of the oxygen contained in the same volume of air.

### What does "ppm" represent?

The letters "ppm" stand for parts per million, which is a term used to describe the concentration of solute dissolved in a solvent. One ppm would equal a concentration of 0.0001%, which is a very dilute concentration.

### What is respiration rate?

The respiration rate refers to the number of breathes an organism takes per minute. Generally speaking, the larger the organism, the slower the organism's respiration rate. For instance, an adult human typically takes about 16 breaths per minute, while a small field mice might breathe 160 times every minute. A number of internal and external factors affect the respiration rate of an organism. A person running requires more oxygen, and therefore, usually has a higher rate of respiration than when the person is standing still. A person in a low oxygen environment would have to breathe at a faster rate to intake the oxygen required to maintain life.

### How does a goldfish breathe?

Although a few fish surface to breathe oxygen from air, most fish extract dissolved oxygen directly from water through their gills. A goldfish has a pair of gills that are located behind its head on both sides of the body. The mouth working in unison with the gills, moves water from the mouth over the gills to remove oxygen from the water. The respiration rate of a goldfish can be measured by counting the number of times each minute the gills and their coverings move.

### What is a direct relationship?

In a direct relationship, as one variable changes, the other variable changes in the same direction. For instance, if one variable increases, the other variable would also increase. If the variable decreases, the other variable also decreases.

### What is an inverse relationship?

In an inverse relationship, as one variable changes, the other variable changes in the opposite direction. For instance, if one variable increases, the other variable would decrease. If the variable decreases, the other variable would increase.