Halfmoon Betta Care Guide: Tank Setup, Diet & Where to Buy

Species Overview#

Halfmoon bettas (Betta splendens) are the show-circuit darling of the betta world — selectively bred over decades to produce a caudal fin that opens to a perfect 180-degree half-circle when the fish flares. They are the same species as every other domestic betta, but the fin geometry makes them the most visually dramatic variety on the market and the most demanding to keep in show condition. A well-kept halfmoon flaring at full spread is what most new betta keepers picture when they imagine the hobby; a poorly-kept halfmoon with shredded, curled, or split fins is how most halfmoon ownership actually ends.

The care fundamentals overlap completely with standard betta keeping — same warm water, same carnivore diet, same labyrinth physiology — but the long, delicate finnage demands tighter discipline on flow, decor, and water quality. This guide covers the halfmoon-specific care that protects the trait you paid for. For the foundational husbandry that applies to every Betta splendens, see our canonical betta fish care guide.

Adult size

2.5-3 in (6-7.5 cm)

Lifespan

2-4 years

Min tank

5 gallons (10+ recommended)

Temperament

Aggressive — single specimen

Difficulty

Beginner-Intermediate

Diet

Carnivore — high protein

What Makes a Halfmoon Betta?#

The defining trait of a halfmoon is a caudal fin that spreads to a full 180 degrees when the fish flares — the trailing edge of the tail forms a straight line from the top ray to the bottom ray, making the fin a true half-circle. This is the standard set by the International Betta Congress (IBC) and is the only criterion that distinguishes a halfmoon from the closely related delta and super-delta tail types. Anything less than 180 degrees at full flare is a delta (under 180) or super-delta (close to but not reaching 180); anything more is an over-halfmoon (OHM, where the tail spreads past 180 degrees and the rays curve forward).

The 180-degree spread is judged at flare, not at rest. A halfmoon at rest looks like any other long-finned betta — the tail droops and folds. Fin spread is only visible when the fish is excited, flaring at a rival, mirror, or photographer. This matters when you are buying: a "halfmoon" sitting motionless in a store cup is not displaying its halfmoon trait, and many fish sold as halfmoons in chain stores turn out to be deltas or super-deltas when they finally flare at home.

Other halfmoon variants include the doubletail halfmoon (DTHM), where the caudal fin splits into two distinct lobes that each spread to 180 degrees, and the over-halfmoon (OHM), where the fin spreads past 180 degrees. OHMs are dramatic at first flare but the over-spread tends to cause ray curl over time as the fin tissue cannot hold the extreme shape.

Size & Lifespan#

Halfmoons reach 2.5 to 3 inches in body length at adult size, with the caudal fin adding another 1 to 1.5 inches at full spread. The body is identical in size to any standard Betta splendens — the halfmoon trait affects fin shape, not body length. A "huge" halfmoon you might see online is almost always being measured fin-tip to fin-tip, not body length. If you want larger body mass, see our giant betta guide; giant halfmoons reach 3 to 4.5 inches of body and exist as a separate selectively-bred line.

Lifespan runs 2 to 4 years with good care, the same as any Betta splendens. Halfmoons do not live shorter lives than other tail types in stable conditions, but they are more likely to die from secondary causes related to fin damage — fin rot from sharp decor, infections from torn fin tissue, stress from constant fin re-growth. Pet store halfmoons are often already 6 to 12 months old at purchase because the dramatic finnage takes months to develop and breeders hold them until they are visually impressive enough to sell, so the practical remaining lifespan is closer to 1.5 to 3 years.

The fragility issue is real and worth understanding before purchase. A veiltail or plakat in the same tank for the same time will look essentially identical at year three. A halfmoon in a tank with a single sharp plant edge or a strong filter output can lose half its caudal spread to tears and re-growth scars within months, and the fish will never look as good as it did the day you brought it home. Tank setup matters more for halfmoons than for any other tail type.

Wild Origin vs. Captive Breeding#

Wild Betta splendens are native to the Mekong River basin in Thailand, Cambodia, Laos, and Vietnam, where they live in shallow rice paddies, slow-moving streams, and stagnant ponds. Wild bettas have short, functional fins — nothing like the flowing finnage of domestic varieties. Wild fish are dull brown or green with a few iridescent scales, and the caudal fin is a simple rounded shape barely longer than the body is deep.

The halfmoon trait is purely a product of selective breeding. The first deliberate halfmoons were developed in the 1980s by European and Thai breeders working from earlier "delta" lines — short-finned bettas with caudal fins that spread to roughly 90 degrees at flare. Decades of selective pairing for ever-wider spread produced the modern 180-degree halfmoon, with IBC show standards codifying the trait in the 1990s. Virtually every halfmoon in the hobby today traces back to those breeding lines, and no wild splendens has ever displayed a true halfmoon caudal.

What this means in practice: there is no "natural" halfmoon habitat to mimic, but the species' native conditions still set the baseline for water parameters. Halfmoons want the same warm, soft, slightly acidic water their wild ancestors evolved in. The fin trait is selectively bred; the husbandry requirements are not.

Water Parameters & Tank Requirements#

Water parameters for a halfmoon match those for any Betta splendens — the differences are in tank size buffer, filter flow, and decor selection, all of which have to scale to protect the fragile finnage.

Ideal Water Parameters#

Target temperature 76 to 82 degrees Fahrenheit (24 to 28 Celsius), pH 6.5 to 7.5, general hardness 3 to 5 dGH, and carbonate hardness 3 to 8 dKH. These match the warm, soft, slightly acidic conditions of the Mekong floodplains where wild Betta splendens still live. Stability matters more than hitting an exact number — a pH that drifts from 6.8 to 7.2 over a week is fine; a pH that swings from 6.5 to 8.0 within 24 hours after a water change is not.

Halfmoons are noticeably more sensitive to ammonia spikes than shorter-finned varieties. The long caudal fin presents more surface area to ammonia exposure, and any low-grade ammonia load will start eroding the trailing edge of the tail before any other clinical symptom appears. A 0.25 ppm ammonia reading that a plakat in a 10-gallon would tolerate for a day or two will trigger fin-edge browning in a halfmoon on the same timeline. Test weekly with a liquid kit (not strips), and run your tank through a complete fishless cycle — ammonia and nitrite both reading 0 ppm within 24 hours of dosing — before adding the fish.

Temperature control is non-negotiable. Below 76 degrees, halfmoon metabolism slows, immune function drops, and fin re-growth stalls. Above 84 degrees, dissolved oxygen drops and the fish surfaces constantly to gulp air through the labyrinth organ, exhausting itself. A submersible adjustable heater rated for your tank size, plus a stick-on or digital thermometer to verify accuracy, is the standard setup.

Minimum Tank Size & Why It Matters#

Five gallons is the absolute floor for a single halfmoon. Ten gallons is strongly recommended and should be the practical default for any keeper who wants the fish to thrive rather than just survive. The extra volume provides a much larger buffer against water quality swings, gives the long caudal fin room to fully spread without bumping decor or glass, and reduces the concentration of dissolved waste that erodes fin tissue over time.

The 2.5- to 5-gallon "betta tanks" sold at chain pet stores were marginal for any betta and are particularly bad for halfmoons. The combination of tight swimming space, undersized filter, and small water volume produces exactly the conditions that shred halfmoon fins fastest. A 10-gallon long (20 by 10 by 12 inches) gives the horizontal swimming room a halfmoon needs to glide between tank ends without catching fins on every side surface. For tank-specific sizing guidance, see our betta fish tank guide.

A larger tank also means more options for compatible tank mates, more room for live planting, and more visual depth for a fish whose entire appeal is visual. Halfmoons in cramped tanks look cramped; the same fish in a 15-gallon planted display looks magnificent.

Filtration & Flow#

Filter flow is the single biggest cause of preventable halfmoon fin damage. The long caudal fin acts as a sail, and any directional current strong enough to move the fin will eventually tear it. Halfmoons fight current constantly when flow is too high, exhausting themselves and accumulating micro-tears along the fin edges that bacteria colonize as fin rot.

Sponge filters are the gold standard for halfmoon tanks. They provide excellent biological filtration with no directional flow — bubbles rise straight up and the water is pulled gently through the sponge material. Drive a sponge filter with an air pump that has adjustable output, and you can dial flow to whatever the fish tolerates. A single sponge filter rated for 1.5 times the actual tank volume (a 15-gallon-rated sponge in a 10-gallon tank) handles bioload comfortably.

If you prefer a hang-on-back filter, choose a model with adjustable flow and baffle the output with a cut water bottle, a piece of filter sponge, or a pre-filter sponge wedged against the spillway. Cover the intake with a pre-filter sponge regardless of filter type — a halfmoon's fins can get pulled into uncovered intakes and shredded in seconds. The goal is enough flow to cycle water through biological media without creating visible surface disturbance across the tank.

Decor & Hiding Spots#

The golden rule for halfmoon decor: nothing sharp, nothing rough, nothing brightly colored that triggers constant flaring. Run your finger along every edge and point of every piece before it goes in the tank. Sharp plastic plants are the worst offenders — they look harmless but the leaf edges are stiff and serrated enough to cut fin tissue with a single brush.

Safe options include silk plants (much softer than plastic), live plants like java fern, anubias, java moss, Amazon sword, Amazon frogbit, and water sprite, smooth river rocks, driftwood with no jagged edges, and ceramic hides without unfinished interior surfaces. Live plants offer the additional benefit of nitrate absorption and a more natural environment, and floating plants give the betta resting spots near the surface where they prefer to spend time.

Indian almond leaves (Catappa) deserve a specific mention. Adding 1 to 2 leaves per 5 gallons of water releases tannins that lower pH slightly, soften water, and provide mild antibacterial and antifungal properties — particularly useful for halfmoons because the tannins help prevent the secondary infections that follow minor fin tears. The leaves tint the water amber, mimicking blackwater conditions of the betta's native floodplain habitat. Replace leaves every 3 to 4 weeks as they break down.

Diet & Feeding#

Halfmoons are obligate carnivores like every other Betta splendens. The dietary requirements are identical, but portion control matters more for halfmoons because excess body weight from overfeeding makes the fish slower and less able to manage its own long fins in the water column.

What Halfmoon Bettas Eat#

A high-quality betta-specific pellet should form the base of the diet. Look for pellets with whole fish, krill, or insect meal as the first ingredient and a protein content of 40 percent or higher. Hikari Betta Bio-Gold and Northfin Betta Bits are reliable mid-tier options that hit those marks. Feed 2 to 4 pellets twice daily for an adult halfmoon, adjusting based on body condition — you want a slight rounded belly after feeding, not a tight pot belly that does not flatten between meals.

Supplement the pellet base with frozen or live foods 2 to 3 times per week. Frozen bloodworms are the gold standard for protein and are accepted enthusiastically by every healthy betta. Frozen brine shrimp adds variety and is slightly lower in protein. Frozen daphnia is excellent for fiber and helps prevent constipation. Live mosquito larvae harvested in summer are an outstanding treat for halfmoons in conditioning and trigger natural hunting behavior.

Avoid generic tropical flakes — most are plant-heavy and do not meet a halfmoon's protein needs. Avoid feeding freeze-dried foods dry; they expand in the gut and cause constipation. Soak any freeze-dried bloodworms or brine shrimp in tank water for 30 seconds before feeding.

Feeding Schedule & Portion Size#

A halfmoon's stomach is roughly the size of its eye. Two to four pellets twice daily is a full meal. Excess food rots on the substrate, spikes ammonia, and causes bloating and swim bladder problems. Skip feeding entirely one day per week to give the digestive system a break and prevent constipation. Remove any uneaten food after 2 minutes.

A reliable schedule: small portion of pellets in the morning and evening, six days a week. On two or three of those days, replace one pellet feeding with frozen bloodworms or brine shrimp. Fast on the seventh day. Adult halfmoons tolerate 3 to 4 day fasts comfortably during a vacation; do not feed double portions before or after to compensate.

Foods to Avoid#

Generic tropical flakes are plant-heavy filler and do not meet betta protein requirements. Goldfish flakes are even worse. Freeze-dried foods fed dry expand in the gut and cause constipation, swim bladder issues, and bloat — soak before feeding. Beef heart and other mammalian protein sources are sometimes recommended online; do not use them. Bettas cannot efficiently process mammalian fat and the diet leads to fatty liver disease over time.

Overfeeding is the second-biggest betta killer after poor water quality. A halfmoon with a visibly distended belly that does not flatten between meals is overfed. The fish will look fat, swim awkwardly, and become more prone to swim bladder disorder. Cut back to 2 pellets per feeding and add a fast day if the belly does not normalize within 3 to 4 days.

Tank Mates & Compatibility#

Halfmoons share the standard betta aggression profile — males will fight other males to the death, and the territorial drive does not respond to training or socialization. Tank mate selection is identical to any other betta variety, with one caveat: halfmoons are slower swimmers due to fin drag, so they are more vulnerable to fin-nipping species than shorter-finned varieties.

Can Halfmoon Bettas Live With Other Fish?#

In a 10-gallon or larger tank, a single male halfmoon can coexist with peaceful, non-flashy species that occupy different water columns. Solo housing is the simpler default and the better choice for first-time betta keepers. A halfmoon alone in a 10-gallon planted tank with no tank mates is often the healthiest setup — no competition for food, no harassment, no risk of fin nipping.

For community options, the safest tank mates include corydoras catfish (sterbai, panda, peppered, or pygmy in appropriate group sizes), nerite snails, mystery snails, harlequin rasboras, ember tetras, and Amano shrimp. Add tank mates first and let them establish in the tank before introducing the betta — adding the betta last reduces the territorial response that triggers aggression toward fish already in "his" tank.

Female bettas can sometimes be kept in sororities (5 or more females in a 20-gallon-plus heavily planted tank) but this is not recommended for halfmoon keepers without prior sorority experience. Aggression in sororities can escalate suddenly and the long-finned females are particularly vulnerable to fin damage from in-fighting.

Species to Avoid#

Never house halfmoons with fin-nipping species (tiger barbs, serpae tetras, skirt tetras, some danio species), other male bettas (immediate fight), other labyrinth fish (gouramis, paradise fish — too similar in appearance and trigger territorial flaring), brightly colored or long-finned fish that bettas perceive as rivals (male guppies, male endlers, cherry barbs in some cases), aggressive cichlids of any kind, or goldfish (require cooler water, produce excess waste).

Halfmoons are particularly vulnerable to fin damage from nipping because their long caudal fin is an attractive target for any fish with a tendency to nip. A tank that works fine for a plakat may produce constant fin damage to a halfmoon. When in doubt, choose tank mates more conservatively for a halfmoon than you would for a shorter-finned variety.

Snail & Shrimp Compatibility#

Nerite snails are generally safe with halfmoons — the hard shell protects them from any aggression, they do not breed in freshwater (so populations stay controlled), and they are excellent algae cleaners. Mystery snails work in larger tanks but produce a noticeable bioload, so limit to 1 to 2 per 10 gallons.

Ghost shrimp are risky. Some halfmoons ignore them; others treat them as live food. If you add ghost shrimp, expect to lose some, and provide dense plant cover for hiding. Amano shrimp are larger and more defensible — they generally hold their own in a betta tank and grow too large for most halfmoons to eat as adults. Neocaridina (cherry shrimp) are too small and brightly colored; an aggressive halfmoon will pick them off one by one. Avoid neocaridina unless you know your specific fish ignores them.

Breeding Halfmoon Bettas#

Halfmoons spawn the same way every other betta does — bubble nest, conditioning, induced spawning, male tends fry. The mechanics are identical to standard betta breeding; the genetic side is where halfmoon breeding gets technically interesting because the trait does not breed true from random pairings.

Setting Up a Breeding Tank#

Use a 10-gallon bare-bottom tank with shallow water (4 to 6 inches), a heater set to 80 degrees Fahrenheit, an Indian almond leaf or styrofoam cup half (cut and floated) to anchor the bubble nest, and dense floating plant cover (frogbit, water sprite, java moss) for the female to hide in. Bare-bottom is the standard choice because it makes spotting eggs and fry easier and simplifies cleaning between spawns.

Condition both parents on heavy live and frozen foods for 2 to 3 weeks before introducing them. The diet should emphasize live blackworms, daphnia, and mosquito larvae, supplemented with frozen bloodworms and brine shrimp. Conditioning builds the energy reserves both fish need for spawning and improves egg quality and fertilization rates.

Introduce the female in a transparent divider, breeder box, or chimney for 24 to 48 hours before releasing. The visual contact lets both fish display courtship behavior — the male should build a bubble nest, the female should display vertical breeding bars. Release the female only when the male has built a substantial nest and the female shows the breeding bars.

Conditioning & Spawning Process#

Spawning runs as a series of "embraces" under the bubble nest — the male wraps his body around the female, eggs are released in clutches of 10 to 30, the male fertilizes them and collects them in his mouth, then deposits them in the nest. The full spawn takes 2 to 6 hours and produces 100 to 500 eggs in total from a healthy proven pair.

Remove the female immediately after spawning ends. The male will become aggressive toward her once eggs are in the nest, and a confined female cannot escape. Leave the male to tend the nest — he will catch falling eggs, rebuild the nest, and guard against predators. Eggs hatch within 24 to 48 hours. Fry remain attached to the nest for another 2 to 3 days while they absorb their yolk sacs, then become free-swimming.

Remove the male once the fry are free-swimming (typically 3 to 4 days post-hatch). Some breeders leave the male in longer, but most modern protocols remove him at free-swimming to prevent accidental fry consumption when his nest-tending instinct fades.

Raising Fry#

First foods are infusoria or vinegar eels for the first 4 to 7 days, then microworms, then baby brine shrimp once fry are large enough to take them (typically 7 to 10 days post-free-swimming). Feeding multiple times per day is essential — fry eat constantly and starve quickly. Maintain water quality with daily small water changes (10 percent) using temperature-matched, dechlorinated water.

Halfmoon trait inheritance is complex. The 180-degree spread results from multiple genes acting together, and a halfmoon x halfmoon spawn produces a mix of halfmoons, super-deltas, deltas, and occasional over-halfmoons — not 100 percent halfmoon offspring. Source breeding pairs from established halfmoon breeders with documented lineage if you want a high percentage of true halfmoons in the spawn. Random retail halfmoon pairings produce highly variable fin types.

Common Health Issues#

Halfmoons share the same disease vulnerabilities as all Betta splendens, with two specific risks amplified by their fin geometry: fin damage and the secondary infections that follow torn fin tissue.

Fin Rot & Fin Damage#

Fin rot is the single most common halfmoon disease and the one most directly tied to husbandry. Symptoms start as ragged or darkened fin edges, progress to receding fin tissue, and in advanced cases reach the body itself. The long caudal fin is the first place fin rot appears because it has the most surface area exposed to bacterial colonization.

Mild fin rot resolves with aggressive water changes (25 percent daily for a week) and pristine parameters (0 ammonia, 0 nitrite, low nitrate). Add Indian almond leaves to the tank for mild antibacterial support and add aquarium salt at 1 tablespoon per 5 gallons (do not exceed this dose for halfmoons — the long fins are sensitive to osmotic stress). Most early fin rot resolves within 7 to 14 days with clean water alone.

Advanced cases with body involvement require antibacterial treatment — kanamycin or erythromycin are the standard choices, dosed in a separate quarantine tank to protect the main tank's biological filter. Identify whether the rot is bacterial (ragged edges with dark borders, advancing slowly) or fungal (cottony white growth on fin edges) before choosing a medication. Bacterial fin rot needs antibacterial; fungal fin rot needs antifungal (methylene blue or commercial fungal treatment).

Distinguish fin rot from environmental fin damage. A halfmoon that snags its tail on a plant leaf gets a clean tear with sharp edges that grow back without intervention as long as water quality is good. A halfmoon with fin rot shows ragged, darkened, advancing tissue loss that does not heal. Treat the underlying cause first — find and remove the sharp decor, fix the water quality, baffle the filter — then treat any secondary bacterial infection.

Velvet, Ich & Columnaris#

Ich (white spot disease) presents as small white granules covering the body and fins, like grains of salt. Raise the temperature to 82 degrees gradually (1 degree per hour) and treat with an ich-specific medication. The elevated temperature accelerates the parasite life cycle, making it vulnerable to treatment faster.

Velvet appears as a fine gold or rust-colored dusting on the body, visible under a flashlight. It is caused by the parasite Piscinoodinium and is more difficult to spot than ich. Treatment involves raising temperature to 82 degrees, dimming lights (the parasite is photosynthetic), and dosing a copper-based medication. Copper kills invertebrates, so move snails and shrimp out before dosing.

Columnaris is a bacterial infection that presents as white or grayish patches on the body and fins, often around the mouth (sometimes called "mouth fungus" although it is bacterial, not fungal). It progresses fast and requires aggressive antibacterial treatment with kanamycin or a combination antibiotic. Catch it early — columnaris can kill within 48 hours in advanced cases.

Swim Bladder Disorder & Bloat#

Swim bladder disorder causes halfmoons to float awkwardly, sink to the bottom, or swim sideways. The most common cause is constipation from overfeeding or a diet lacking fiber. Treatment: fast the fish for 2 to 3 days, then feed a small piece of blanched, deshelled green pea (the fiber acts as a laxative). If symptoms persist after fasting, the cause may be bacterial and antibiotic food may be needed.

Epsom salt baths can help in stubborn cases — 1 tablespoon Epsom salt per gallon in a separate container, fish bathed for 10 to 15 minutes, then returned to the main tank. The magnesium relaxes intestinal muscles and helps clear blockages. Do not use aquarium salt for this purpose; it does not have the same laxative effect and can stress the fish at higher concentrations.

Prevention is straightforward: feed measured portions twice daily, soak any freeze-dried food before feeding, fast one day per week, and rotate in daphnia or frozen mysis for fiber. A halfmoon with visible body taper (slight narrowing behind the gills) is well-fed; a halfmoon with a tight pot belly that does not flatten between feedings is overfed.

Where to Buy & What to Look For#

Sourcing a true halfmoon is harder than sourcing a standard veiltail. The mislabeling rate at chain stores is high — fish sold as "halfmoon" or "halfmoon plakat" are often deltas or super-deltas that have never been verified at full flare. Specialty local fish stores and reputable breeders are the better sources for genuine halfmoons.

Online vs. Local Fish Store#

Local fish stores let you inspect the actual fish before purchase. You can ask staff to flash a mirror at the cup to trigger flaring and verify the 180-degree caudal spread before you commit. You can check fin condition, color saturation, eye clarity, and behavior in person. You skip shipping stress entirely. For most halfmoon buyers, LFS sourcing is the better default.

Online sourcing through breeder marketplaces (Aquabid, breeder Facebook groups, dedicated betta importers) opens access to rare colors, specific fin variants (like over-halfmoons or doubletail halfmoons), and proven show-quality lines that local stores rarely carry. The trade-off is shipping stress and the inability to verify the fin trait before delivery. Use overnight shipping only, schedule arrival for a day you will be home, and have a quarantine tank cycled and warmed before the fish arrives.

Healthy Halfmoon Betta Checklist#

The fin curl issue deserves specific attention. Some halfmoons develop curled rays at the trailing edges of the caudal fin — a condition where the rays bend forward and the fin loses its clean half-circle shape. Mild curling can be genetic (over-halfmoon lines are particularly prone) or environmental (from sharp decor or strong flow). Severe curl rarely improves and the fish will not show its halfmoon trait properly even after relocation to a clean tank. Inspect for fin curl before buying — minor edge wear is forgivable on a young fish, but visible ray curl is a permanent condition you are paying full price for.

Price Range & What Affects Cost#

Standard pet store halfmoons run $15 to $30. Premium colors (galaxy, koi, dragon scale, mustard gas) at specialty LFS run $30 to $60. Show-quality halfmoons from named breeders, particularly imports from Thailand, can run $50 to $200 or more. Doubletail halfmoons and over-halfmoons command premiums because they are harder to breed reliably.

Color and fin quality drive most of the price difference. A clean solid red halfmoon with perfect 180-degree spread costs more than a marbled fish with the same spread. A koi halfmoon with strong pattern definition costs more than a less-defined koi. Brand-name breeders (Indo Aquatics, various Thai breeders, IBC-certified show breeders) carry premium pricing because their lineage is documented and the trait is more consistent.

For a first halfmoon, a $20 to $40 specimen from a reputable LFS is the right price range. Save the show-quality budget for after you have kept a halfmoon successfully through one full lifespan and understand how easily the fins can be damaged. There is no shame in starting with a less-expensive halfmoon while you build the keeping skills the variety demands.

Quick Reference#

• Tank size: 5 gallons minimum, 10 gallons strongly recommended
• Temperature: 76-82 degrees Fahrenheit (24-28 Celsius) — heater required
• pH: 6.5-7.5
• Hardness: 3-5 dGH, 3-8 dKH
• Ammonia / nitrite: 0 ppm always — halfmoons are more sensitive to fin damage from ammonia than shorter-finned varieties
• Nitrate: Below 20 ppm with weekly water changes
• Filtration: Sponge filter (preferred) or baffled HOB — flow must be near zero
• Decor: Silk plants, live plants, smooth driftwood, ceramic hides — no sharp plastic, no rough edges
• Diet: High-protein pellets (40 percent or higher) twice daily, frozen bloodworms or brine shrimp 2-3x weekly, fast one day per week
• Tank mates: Corydoras, nerite snails, harlequin rasboras, ember tetras, Amano shrimp — solo is the simpler default
• Aggression: Single specimen — never two males together; sororities not recommended for halfmoon keepers
• Lifespan: 2-4 years
• Adult size: 2.5-3 inches body length plus 1-1.5 inches caudal fin spread
• Identifying trait: Caudal fin spreads to 180 degrees at full flare (not at rest)
• Difficulty: Beginner to intermediate — fin care is more demanding than other tail types

For the foundational care principles that apply to every Betta splendens — including bubble nesting, labyrinth physiology, and the full disease guide — see the canonical betta fish care guide. For tank-specific guidance, the betta fish tank guide covers sizing and setup in more depth. If you are weighing other betta varieties, our giant betta, koi betta, and veiltail betta pages cover those alternatives. Or browse the broader freshwater fish hub for related species.