For most established freshwater aquariums, a 10-25% water change weekly is ideal. New tanks or heavily stocked tanks may need more frequent changes. Always use a water conditioner to remove chlorine and chloramines from tap water.

Common causes include: uncycled tank (ammonia/nitrite poisoning), overstocking, poor water quality, disease from new fish, incorrect temperature, or stress. Test your water parameters immediately and ensure your tank was properly cycled before adding fish.

Reduce light to 8 hours daily, don't overfeed, perform regular water changes, and add live plants to compete with algae. For green algae on glass, use an algae scraper. Avoid chemical algae removers - address the underlying causes instead.

Yes, but carefully! Choose peaceful community fish with similar water parameter requirements. Research each species' temperament, adult size, and preferred tank mates. Avoid mixing aggressive species with timid ones, and ensure no fish will outgrow others to become predators.

While not strictly necessary, live plants offer many benefits: they absorb nitrates, provide oxygen, offer shelter for fish, and compete with algae. Beginner-friendly plants include java fern, anubias, java moss, and hornwort. Start with a few easy plants and expand as you gain experience.