The 50 Most Common Aquarium Questions According to Search Data

The most common aquarium questions are about which fish to choose, which fish live together, how to set up and cycle a tank, and whether unusual animals such as axolotls, snakeheads and crabs can be kept at home. This list of fifty questions is built from the terms shoppers search for most on FishyHub, from bettas and guppies to plecos, puffers and turtles, and answers each one briefly for US fishkeepers.

Key Findings

• FishyHub search data shows shoppers search most for fish by name, with bettas, guppies, tetras, angelfish, discus, plecos, oscars, flowerhorns and arowanas in the very high search tier.
• FishyHub search data shows shrimp, snails, crabs and turtles in the very high search tier, which is why invertebrate and turtle questions feature strongly here.
• FishyHub search data shows axolotls, frogs, isopods and jellyfish in the high search tier, prompting questions about keeping animals other than fish.
• FishyHub search data shows setup terms such as filter, gravel, sand, driftwood and carbon dioxide in the moderate tier, behind livestock names.
• FishyHub data shows guppies, tetras, danios, rasboras, corydoras and Neocaridina shrimp in the US entry-level price tier, the usual answer to beginner questions.
• FishyHub data shows halfmoon plakat bettas draw very high buyer interest from US users.

Choosing Fish

1. What is the best fish for a beginner? Hardy, peaceful fish such as guppies, platies, danios, rasboras and corydoras. All sit in FishyHub's US entry-level price tier.
2. Can a betta live with other fish? Often, with calm, short-finned tank mates such as corydoras or small rasboras. Never with another male betta.
3. How big a tank does a betta need? Bigger than a bowl. A filtered, heated tank of a few gallons or more keeps water stable.
4. Do bettas need a heater? In most US homes, yes. Bettas are tropical and sluggish in cool rooms.
5. Why are halfmoon plakat bettas so popular? They combine show colour with short, practical fins. On FishyHub they draw very high US buyer interest.
6. How many tetras should be kept together? Enough to form a proper school. A larger group is calmer and more colourful.
7. Are guppies easy to breed? Very. Females give birth to live young regularly, so expect fry unless you keep only males.
8. Can angelfish live with neon tetras? Only while the angelfish are small. Adults will eat small tetras.
9. Are discus hard to keep? They need warm, soft, very clean water and frequent water changes, so they suit experienced keepers.
10. How big do oscars get? Large. Despite entry-level prices on FishyHub, an oscar needs a big tank and strong filtration.
11. Are flowerhorns aggressive? Usually, yes. Most are kept alone and become very interactive with their owners.
12. Can I keep an arowana in the US? Silver, black and Jardini arowanas, yes. Asian arowanas are off-limits as an endangered species under US law.
13. Are snakeheads legal in the US? No. The snakehead family is restricted under federal wildlife law.
14. What do plecos eat? Algae wafers, vegetables and, for many species, driftwood to rasp. Some species also need meaty foods.
15. Will a pleco clean my tank? Not on its own. Plecos produce plenty of waste, so filtration and water changes still matter.
16. Are corydoras good tank mates? Yes. They are peaceful, social bottom dwellers best kept in groups on soft sand.
17. What fish eat algae? Otocinclus, bristlenose plecos and some loaches, along with Amano shrimp and nerite snails.
18. Can goldfish live without a heater? Yes. Goldfish prefer cooler water than tropical fish.
19. Can goldfish live with tropical fish? Not ideally. They prefer cooler water and produce more waste.
20. Are koi aquarium fish? Koi are pond fish. They outgrow nearly every indoor aquarium.
21. What do pufferfish eat? Snails, shellfish and frozen meaty foods. Hard foods keep their ever-growing teeth worn down.
22. Are bichirs aggressive? Mostly peaceful, but they will eat any fish small enough to swallow.
23. Is a gar a good aquarium fish? Only for keepers with very large tanks. Gar grow long and need room to cruise.
24. Can eels live in a freshwater aquarium? Spiny eels and fire eels can, in tanks with soft sand and secure lids.
25. What are the easiest cichlids? Convicts, kribensis and many African cichlids are hardy. Rams and apistogramma need softer, cleaner water.

Shrimp, Snails and Other Animals

1. Are shrimp easy to keep? Neocaridina shrimp are, once a tank is cycled and stable. Caridina shrimp need softer water.
2. Will fish eat shrimp? Larger fish will. Shrimp do best with small, peaceful fish and plenty of plants.
3. Are snails good for an aquarium? Most are. They eat algae and leftover food.
4. How do I get rid of pest snails? Feed less, remove them by hand, or add assassin snails.
5. Can crabs live in a fish tank? Some can, but many freshwater crabs need land to climb onto and a secure lid.
6. Are vampire crabs aquatic? Semi-aquatic. They need a paludarium with both land and water.
7. Can turtles live with fish? Rarely. Turtles eat fish and need a basking area and UV lighting.
8. Are axolotls legal in my state? It depends. Some states restrict axolotls, so check your state's wildlife rules first.
9. Can you keep jellyfish at home? Yes, in specialised round tanks with gentle flow. Standard aquariums are unsuitable.
10. What are isopods used for? They clean up waste in bioactive terrariums and vivariums.

Tank Setup and Care

1. What size tank should a beginner buy? A medium tank is more forgiving than a very small one, because water conditions change more slowly.
2. How do I cycle a fish tank? Add an ammonia source and let bacteria grow until tests no longer detect ammonia or nitrite.
3. Do I need a filter? Almost always. A filter houses the bacteria that keep fish waste in check.
4. Sand or gravel? Sand suits corydoras and other sifters; gravel is easier to vacuum.
5. Do aquarium plants need carbon dioxide? Easy plants such as Java fern and Anubias do not. Carpeting plants often do.
6. Is driftwood safe? Yes, when bought for aquariums. It may tint the water brown at first.
7. How often should aquarium water be changed? Small partial changes on a regular routine work better than rare big ones.

Saltwater and Reef

1. Is a saltwater tank hard to keep? Harder than freshwater, mainly because salinity and water quality must stay stable.
2. Do clownfish need an anemone? No. Captive-bred clownfish thrive without one.
3. What corals are easiest for beginners? Soft corals, mushrooms and zoanthid polyps. SPS corals are best left until later.
4. Why are tangs expensive? Most are wild-caught and need large tanks. On FishyHub, tangs sit in the US collector tier.

Buying and Shipping

1. Is it safe to buy fish online? Yes, from reputable sellers who ship overnight and offer clear arrival policies.
2. How are fish shipped in winter? In insulated boxes with heat packs, by overnight courier.
3. What should I do when fish arrive? Float the bag, match temperature and water slowly, then release the fish without the bag water.
4. Why are some fish so expensive? Size, rarity, slow growth and selective breeding. Arowanas, flowerhorns and many reef fish sit in FishyHub's US collector tier.

Methodology

FishyHub does not record full questions; its search data captures the terms shoppers type, such as "betta", "axolotl" or "filter". These questions were built by taking the terms in FishyHub's very high, high and moderate search tiers over the period from October 2024 to October 2026 and pairing each with the questions hobbyists most commonly raise about it. Answers draw on FishyHub's US listing tiers, price tiers and buyer interest where relevant, and on general hobby knowledge elsewhere.

Search terms combine the US and Singapore markets. The order of the questions follows topic, not popularity, and FishyHub does not measure search engines or the wider web.

Frequently Asked Questions

What is the most common aquarium question?

Which fish to start with. Beginner questions cluster around bettas, guppies and tetras, all in FishyHub's very high search tier.

Where does this search data come from?

From the terms shoppers type into FishyHub's search, grouped into tiers. FishyHub does not capture full sentences or questions.

Why are axolotl questions on an aquarium list?

Axolotls sit in FishyHub's high search tier, so many fishkeepers clearly want to know whether they can keep one.

How to Cite This Page

Source: FishyHub, "The 50 Most Common Aquarium Questions According to Search Data" (2026), https://fishyhub.com/us/blogs/blog-detail/the-50-most-common-aquarium-questions-according-to-search-data