What fish, coral, and inverts can live with the Pajama Cardinalfish (Sphaeramia nematoptera). Tank mate compatibility broken into good / caution / avoid buckets - tank size minimum: 30 gallons minimum.
These species coexist well with the Pajama Cardinalfish in an appropriately-sized tank.
Workable pairings if the tank is large enough or the introduction is staged correctly.
Don't combine these with the Pajama Cardinalfish. Outcome is usually death of one species or chronic stress.
Pajama cardinalfish are slow + peaceful. Distinctive appearance: yellow head, black mid-band, polka-dot rear. School loosely in groups of 3-7. Mouthbreed eggs (less prolifically than banggai). Captive-bred specimens are far hardier than wild-caught.
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Browse Pajama Cardinalfish listings → Pajama Cardinalfish care guideSuccessful long-term keeping of any aquarium species comes down to three pillars: tank size + footprint, parameter stability, and tankmate compatibility. Undersize any one and the rest collapse. Use our stocking calculator, tank volume calculator, and tankmate compatibility guides before adding anything new.
Quarantine is the single most important husbandry practice and the one most aquarists skip. A 30-day quarantine period in a separate tank lets you observe behavior, catch parasites + bacterial infections before they spread, and treat aggressively without harming your display. Saltwater fish should be treated prophylactically with copper + praziquantel during QT; freshwater fish should be observed for ich, velvet, flukes, columnaris, and dropsy. See our QT timeline calculator + disease symptom matcher.
Water quality is the second pillar. Test ammonia + nitrite + nitrate weekly with reliable kits (API Master Test Kit for FW, Salifert + Hanna for SW). Reef tanks add alkalinity (target 7.5-9.5 dKH), calcium (380-450 ppm), magnesium (1280-1450 ppm), phosphate (0.02-0.10 ppm). Use our water parameter checker to score your readings.
How long should I quarantine before adding to display? 30 days minimum, with prophylactic treatment for SW fish (14d copper + 2x prazi). FW fish: 30d observation + general cure for flukes. See QT timeline calculator.
What size tank do I need? Always research the species's adult size + activity level + territoriality. Many fish marketed as "starter species" actually need 75g+ at adult size. Use our stocking calculator to plan correctly.
Wild-caught vs captive-bred? Captive-bred whenever possible. They acclimate faster, accept prepared foods, are immune-resilient, and don't deplete wild populations. ORA + Sustainable Aquatics + Bali Aquarich + Wattley Discus are top breeders. Browse our originator directory.
What if my fish stops eating? Test water first - 90% of "not eating" issues trace to water quality. Then check for parasites (white spots, flashing, breathing rate). Use our aquarium problem diagnoser.
How do I acclimate a new fish? Drip acclimation over 60-120 minutes for sensitive marine species, 30-60 min for hardy freshwater. Use our acclimation drip rate calculator.
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