--- title: The fish tank: water, gills, heaters and the right neighbours — a lesson of Mova's school · trees and pragmatics description: «The fish tank: water, gills, heaters and the right neighbours», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Fish breathe the oxygen dissolved in water through their gills, and their droppings make waste that would po --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / The fish tank: water, gills, heaters a… # The fish tank: water, gills, heaters and the right neighbours Lesson 203 of the biology course of Mova's primary school: 14 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/). - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/1/) — Fish breathe the oxygen dissolved in water through their gills, and their droppings make waste that would poison them if friendly bacteria in the filter did not turn it into something safer. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/2/) — That is why a brand-new tank filled with tap water and stocked with fish the same day often goes wrong: the helpful bacteria have not grown yet. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/3/) — Waiting while they grow is called cycling the tank. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/4/) — A good owner also checks what each fish needs, warm or cool water, fresh or salt, and how big it will grow, because a fish that fits in another fish's mouth may become its dinner. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/6/) — Fish take oxygen from water through their gills, and a filter, moving water and air bubbles help mix more oxygen into the water. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/7/) — Tropical fish such as angelfish and neon tetras need warm water kept steady by a heater, while goldfish need cooler water, so they are usually kept apart. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/8/) — Fish need only as much food as they can eat in a couple of minutes; leftover food rots and makes the water cloudy and dirty. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/9/) — Fish have no eyelids, so they sleep with their eyes open, resting quietly near the bottom or among plants, and some parrotfish wrap themselves in a bubble of slime to sleep. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/10/) — Fish that are small enough to fit in another fish's mouth may be eaten, so owners check how big each fish will grow before putting them together. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/11/) — Betta fish need more room than a tiny bowl, plus warm, filtered water, and male bettas fight each other, so they are kept one male per tank. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/12/) — A pleco sucking on the glass is scraping off algae (a green slimy growth of tiny plant-like living things) with its sucker mouth, and some kinds of pleco grow much bigger than the shop said. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/13/) — Fish notice movement and shadows, which often mean a bird is hunting, and they also feel movements in the water with a line of sensors along their sides called the lateral line. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/14/) — Real clownfish like Nemo live in warm sea water among anemones (soft stinging sea animals that look like flowers), and after the Finding Nemo films many people were reported to buy clownfish they could not care for. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/203-the-fish-tank-water-gills-heaters-and-the-right-neighbours/15/) — Living plants use up some fish waste, add oxygen in the light and give fish places to hide. - ← previous: [Hamsters, gerbils and pet rats and mice](https://md.mova.elamur.ai/free/en/corpora/school/biology/202-hamsters-gerbils-and-pet-rats-and-mice/) - next →: [Goldfish and pond fish: the three-second memory myth](https://md.mova.elamur.ai/free/en/corpora/school/biology/204-goldfish-and-pond-fish-the-three-second-memory-myth/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)