Biology and environment interact. First of all, the environment affects the survival of living things. Environment includes biological factors and abiotic factors, which include sunlight, air, temperature, moisture and soil. Biological factors include all kinds of organisms that affect the survival of organisms. Environmental changes will directly affect the survival of living things. Creatures must adapt to the environment to survive, otherwise they will be eliminated. When organisms adapt to the environment, their activities will also have an impact on the environment. It can be seen that biology and environment are interactive. (1) In this question, abiotic factors that affect the "fat" life of goldfish include rockeries, beaches, shells, lights and a living space in the environment, all of which will have an impact on organisms. The biological factors that also affect the "fat" life of goldfish are: small trees and goldfish are "smart"

(2) Biological factors include predation, competition, cooperation and parasitism. Therefore, the biological relationship between goldfish and young trees is mutual assistance (interspecific assistance), and the biological relationship between goldfish "beauty" and "intelligence" is struggle (intraspecific struggle).

(3) If the goldfish is taken out of the fish tank, it will die soon, indicating the influence of water in the environment on the goldfish, that is, the environment affects the living things; If the water in the fish tank is not changed for a long time, the water in the fish tank will become turbid. The reason is that goldfish manure pollutes the water source, indicating that organisms will also affect the environment.

So the answer is:

(1) rockeries, beaches, shells and lights; Small trees and goldfish are "smart" and "beautiful"

(2) Mutual assistance (interspecific assistance); Struggle (intraspecific struggle)?

(3) the environment affects organisms; Biology affects the environment.