In the normal development stage, children become ill for various reasons and maybe hospitalised. Illnesses and hospitalization are major sources of stress for any growing child. In addition to being admitted to the hospital, unknown environment, unknown people in this environment, unknown equipment, scary voices, thought of physical harm, fears such as separation from the family, etc. Different degrees of stress occur for reasons. In addition to these, children face many problems related to physical limitations caused by hospitalization due to illness, and they experience negative emotions such as anxiety, fear, and anxiety. On the day the child is admitted to the hospital, the child and his family experience high levels of anxiety. Children's anxiety and fear may negatively affect their ability to understand the explanations to be made correctly, to interpret events realistically, to make appropriate decisions, and to participate in care. Various treatment methods such as therapeutic games, art therapy, drawing, occupational therapy, animal-assisted practices/activities (HDU) are applied in the hospital environment to improve the child's coping skills and to reduce negative emotions such as pain, anxiety, stress, and fear. The animal-assisted practice is activities that offer various opportunities to improve the quality of life and provide entertainment and therapeutic benefits. Although the use of animal-assisted applications is widespread abroad, its use in our country and the rate of reflection on the results of the study is quite limited. In the researches, interaction with such animals; has been determined to be psychologically, emotionally, socially, and physically supportive in children. It is planned to use goldfish in this study. Aquarium fish is one of the ornamental fish sold in more than 125 countries and more than 2500 species globally. No study has been conducted on the effects of aquarium fish, which are reported to have positive effects and provide calming when applied with adult age groups within the scope of animal-assisted practices, on anxiety, fear, psychological and emotional well-being in children treated in a clinical setting. This study will be conducted to examine the effects of animal-assisted practice on anxiety, fear, the psychological and emotional well-being of children hospitalised.

Inclusion Criteria:

• Being 8 years old and over, 10 years old or younger,
• Hospitalization due to an acute illness,
• Not afraid of aquarium fish to be used in practice,
• Not being allergic to fish and fish food,
• Not having physical, auditory, visual, and cognitive disabilities that would prevent the aquarium fish from feeding twice daily and in the aquarium within the scope of HDU,
• Staying in the pediatric clinic for three days,
• Not having a speech disorder that will prevent them from communicating.

Exclusion Criteria:

• Having a physical, auditory, visual, and cognitive disability that prevents the aquarium fish from feeding twice daily,
• Afraid of goldfish,
• Being allergic to fish and eating.