- Activated Carbon
- Aeration
- Air Stone
- Algae
- Algae Bloom
- Ammonia (NH₃)
- Ammonia Poisoning
- Ammonia Spike
- Anaerobic Bacteria
- Angelfish (Pterophyllum scalare)
- Aquascaping
- Azure Damselfish (Chrysiptera hemicyanea)
- Bacterial Bloom
- Baffle
- Banggai Cardinalfish (Pterapogon kauderni)
- Beneficial Bacteria
- Betta (Betta splendens)
- Bioload
- Biological Filtration
- Black Beard Algae (BBA)
- Blackwater Aquarium
- Brackish Water
- Canister Filter
- Carbon Dioxide (CO₂)
- Cardinal Tetra (Paracheirodon axelrodi)
- Carnivore
- Chloramine
- Chlorine
- Cloudy Water
- Clown Goby (Gobiodon spp.)
- CO₂ Injection
- Coldwater Fish
- Column Feeder
- Columnaris (Cotton Wool Disease)
- Convict Cichlid (Amatitlania nigrofasciata)
- Cycling (Nitrogen Cycle)
- Detritus
- Diatoms
- Discus (Symphysodon spp.)
- Dissolved Oxygen
- Driftwood
- Drop Checker
- Dropsy
- Ecosystem Aquarium
- Eutrophication
- External Filter
- Feeder Fish
- Filter Media
- Fin Rot
- Firefish Goby (Nemateleotris magnifica)
- Flow Rate
- Fluorescent Lighting
- Fungus (Fungal Infections)
- Gill Flukes
- GPH (Gallons Per Hour)
- Gravel Vacuum
- Green Water
- Guppy (Poecilia reticulata)
- Hard Water
- Harlequin Rasbora (Trigonostigma heteromorpha)
- Heater
- HOB (Hang-On-Back) Filter
- Hospital Tank
- Ich (Ichthyophthirius multifiliis)
- Ich (White Spot Disease)
- Indian Almond Leaves
- Jack Dempsey (Rocio octofasciata)
- Jungle Val (Vallisneria)
- KH (Carbonate Hardness)
- Lack of Oxygen (Hypoxia)
- Live Rock
- Livebearers
- Mechanical Filtration
- Molly (Poecilia sphenops)
- Moss Ball
- Mouthbrooder
- Neon Tetra (Paracheirodon innesi)
- New Tank Syndrome
- Nitrate (NO₃)
- Nitrite (NO₂)
- Nitrite Poisoning
- Ocellaris Clownfish (Amphiprion ocellaris)
- Omnivore
- Oscar (Astronotus ocellatus)
- Osmosis
- Parasites (External & Internal)
- pH
- pH Crash
- Planted Tank
- Platy (Xiphophorus maculatus)
- Rainbow Shark (Epalzeorhynchos frenatum)
- Six-Line Wrasse (Pseudocheilinus hexataenia)
- Substrate
- Sump
- Swim Bladder Disorder
- Swordtail (Xiphophorus hellerii)
- Tannins
- Tap Water Contaminants
- Toxic Tank Syndrome
- Turnover Rate