Fish. Date back 425-500 million years ago. Early fish were called Ostracoderms and were slow, bottom-dwelling animals covered with thick, bony plates and scales. Believed to be the first animal with a backbone. Two (2) groups evolved from the Ostracoderms that exist today:
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Date back 425-500 million years ago. Early fish were called Ostracoderms and were slow, bottom-dwelling animals covered with thick, bony plates and scales. Believed to be the first animal with a backbone.
Skin of the fish contains glands that produce a slimy mucus, which makes it slippery and provides protection from bacteria. Skin contains chromatophores, pigment cells that give fish their color.
Swim bladder: located in abdominal cavity; filled with gasses produced by blood, which enables fish to maintain a particular depth.
Fish have taste buds in their mouth, on their lips, and on the body and fins. Sense of smell is highly developed. Some have taste buds on barbels, whisker-like projections around the mouth.
Predator fish have teeth on front of jaws, roof of mouth, and throat teeth just in front of esophagus to usually consume prey whole. Sharks and piranha have cutting teeth for biting pieces from their prey.
Some fish have rasp-like teeth to scrape plant and animal growth from rocks. Some species only have teeth in the pharynx to grind food before it enters esophagus.
Food enters esophagus – stomach – intestine – anus
Lung fish, shark, and rays have a cloaca through which waste material passes.
**Fish should be fed 2-3 times a day and receive only what they can consume in 3-5 minutes.**
Superclass: Pisces (all fish)
Class: Agnatha or Cyclostomata (jawless fish, have sucking or filter-feeding mouths)
Class: Chondrichthyes – fish with cartilaginous skeletons
Class: Osteichthyes – fish with bony skeletons
Subclass: Actinopterygii (ray-finned fish) – 34 orders
Determining the number of fish that can be put into a tank, you must first multiply the length x width to determine the square inches of surface area.
Tropical freshwater fish: no more than 1” of fish for every 10 sq. ins.
Cold freshwater fish: 1” of fish for every 30 sq. ins.
Marine fish: 1” for every 48 sq. ins.
The aquarium should be in a draft free area and out of direct sunlight.
Fish reproduce by the fertilization of the female’s eggs by the sperm (milt) of the male. This process is called spawning in fish.
Types of Reproduction
Egg-Scatterers:Fish that lay eggs in a haphazard manner of floor of an aquarium. No parental care of eggs or young; must be careful so that parents don’t eat the fry (newly hatched eggs). Exs: Barbs, Danios, Goldfish
Egg buryers: Fish that lay their eggs in the mud of rivers and ponds that dry up. Adults die when water dries up. The eggs survive in the mud, and when the next rain comes, the young hatch. Ex: killifish
Egg depositers: Excellent parents. Select their own mates. Clean off a nesting site where the female deposits the eggs and the male fertilizes them. The parents usually take turns guarding the nest. They constantly fan the nest and eggs to keep dirt and dust from settling on them. After the young hatch, the parents keep watch over them for several days to protect them from enemies. Exs: Cichlids, Catfish, Sunfish
Mouth brooders: Fish that carry their eggs in their mouth until they hatch, after which they may continue to be carried there until they can fend for themselves. After the eggs are deposited and fertilized, the female (usually) goes around and picks up the eggs by mouth. During this period of 2-3 weeks, the parent doesn’t eat. Ex: Betta
Nest builders: Construct a nest in which eggs are deposited. Usually made by the male. After eggs are fertilized, the female should be removed because the male will become aggressive. The male guards the nest until fish hatch. Ex: Gouramis
Live Bearers: Give birth to 20-200 young fry. Females store the milt in their oviducts for several months, thus several broods can be produced from one mating. Exs: Guppies, Swordtails, Mollies
Some signs that may indicate a disease problem include:
Unusual behavior, leaning to the side, fins not extended, caudal fin closed or rolled, slow movement, respiration faster than normal, on surface gasping for air, fish rubbing against decorations, fish not eating, fish thin with sunken sides, abnormally large or swollen bellies, abnormal color, frayed fins, malformation of back, cloudiness of the eyes, and scales sticking out away from the body.
Infectious: Caused by pathogenic organisms present in the environment or carried by other fish. They are contagious. Include parasites, bacteria, viruses, and fungi.
Noninfectious: Not contagious. Caused by environmental problems, nutritional deficiencies, or genetic defects. Usually cannot be cured by medications.
Choose 2 infectious and 2 noninfectious diseases. Write down their names, symptoms, causes, treatments, & prevention for each.
1.) What are the 2 groups that evolved from Ostracoderrms?
2.) Name & describe 4 types of fish scales.
3.) Define chromatophores.
4.) What’s the purpose of of a swim bladder?
5.) What is a lateral line?
6.) How do fish mouth structures differ?
7.) Name the complete scientific classification for one freshwater and one saltwater fish.
8.) List 3 factors that increase ammonia and nitrate levels.
9.) Name & describe 4 ways fish reproduce.
10.) List 6 signs that may indicate a disease problem.