🦈 Top 9 Freshwater “Sharks” for Aquariums: Vet Guide 2025 🩺

By Dr Duncan Houston BVSc – Freshwater “sharks” are sleek, impressive fish that add movement and style to aquariums. These species—actually Cyprinids or catfish—are not true sharks but have a striking look. Here’s an expert dive into the top 9 options, their care needs, tank setups, and fish‑veterinary advice to help you keep them healthy and thriving in 2025.

📋 What counts as a freshwater “shark”?

These fish are called “sharks” due to their body shape, dorsal fins, and sleek swimming style—they belong to carp, barb, or catfish families, not actual sharks :contentReference[oaicite:3]{index=3}.

Most are active mid‑water or bottom swimmers, some are peaceful, others territorial or predatory. They range in size from 4″ (roseline) to 3 ft (black shark). Knowing their adult size and behavior is vital before buying.

1. Bala Shark (Balantiocheilos melanopterus)

• Size & Tank: Up to 13–14″; needs ≥125 gal per fish in a school :contentReference[oaicite:4]{index=4}.
• Temperament: Peaceful and schooling—best in groups of 5+ in spacious tanks.
• Care Tips: Provide open swimming areas, stable water (pH 7–8), and strong filtration. Jumpers—cover tank securely.
• Vet insight: Avoid chronic stunting by upgrading tank size as they grow. Use Ask A Vet for help with dietary balance and stress.

2. Rainbow Shark (Epalzeorhynchos frenatum)

• Size & Tank: 6–7″; 50–75 gal with caves or driftwood to define territory :contentReference[oaicite:5]{index=5}.
• Temperament: Semi‑aggressive and territorial; mix responsibly with mid‑level swimmers and plant barriers.
• Diet: Omnivore—flakes, bloodworms, algae wafers; supplement protein and plant matter.
• Vet insight: Monitor fin damage; aggressive interactions can increase stress and disease—use daily observation and Ask A Vet if concerns arise.

3. Red‑Tail Black Shark (Epalzeorhynchos bicolor)

• Size & Tank: 6–7″; prefers ≥50–75 gal with open space and hiding spots :contentReference[oaicite:6]{index=6}.
• Temperament: Highly territorial—avoid keeping multiple unless tank is very large.
• Diet: Similar to rainbow shark; monitor for aggression-related fin stress.
• Vet insight: Provide driftwood caves to reduce aggressive chasing. Use AquaCare for water‑calming supplements during stress or transition.

4. Roseline Shark / Denison’s Barb (Sahyadria denisonii)

• Size & Tank: 4–6″; school of 6+ in ≥30 gal :contentReference[oaicite:7]{index=7}.
• Temperament: Peaceful, active, suitable for community tanks.
• Care Notes: Prefer planted aquaria with stable water; wild-caught supplies should be avoided due to conservation concerns.
• Vet insight: Best beginner shark—use Ask A Vet to monitor health when sourcing captive-bred stock and maintaining groups.

5. Violet Blushing Shark (Epalzeorhynchos munense)

• Size & Tank: Up to 12″; needs ≥125 gal :contentReference[oaicite:8]{index=8}.
• Temperament: Mildly aggressive; best with robust tankmates and room to patrol.
• Care Tips: Provide rock shelters and driftwood; monitor color fading which indicates stress.
• Vet insight: Larger sharks like these need consistent diet including iodine supplements—AquaCare can help prevent deficiency.

6. Black Shark / Iridescent Shark Catfish (Pangasianodon hypophthalmus)

• Size & Tank: Up to 2–3 ft; requires ≥200 gal :contentReference[oaicite:9]{index=9}.
• Temperament: Schooling bottom‑dweller; overly stressful in small tanks.
• Special Care: Poor vision—avoid startling; include shaded hideouts.
• Vet insight: Use Ask A Vet if trauma from tank shock or injuries due to stress occur.

7. Harlequin Shark (Labeo cyclorhynchus)

• Size & Tank: Up to 6″; needs ≥30 gal :contentReference[oaicite:10]{index=10}.
• Temperament: Semi‑aggressive and territorial.
• Diet: Omnivore with algae and protein needs.
• Vet insight: Provide stable territories—stress leads to fin damage and increased disease risk.

8. Siamese Algae Eater (SAE) & Chinese High-Fin Banded (not on PetMD list)

• SAE: 6″, peaceful algae eater, needs ≥30 gal, active cleaner.
• Chinese High-Fin Banded Shark (Myxocyprinus asiaticus): Up to 3 ft; requires pond‑size ≥300 gal :contentReference[oaicite:11]{index=11}.
• Vet insight: Chinese sharks are unsuitable for most home tanks—intervene early if growth is stunted or health declines.

9. Columbian Shark Catfish (Ariopsis seemanni)

• Size & Tank: 12″; needs ≥75 gal, often prefers brackish water :contentReference[oaicite:12]{index=12}.
• Temperament: Peaceful, schooling—but venomous spines in pectoral fins; always wear gloves.
• Care Tips: Requires tight lid, moderate current, gradual salinity increase if desired.
• Vet insight: Sting first-aid: hot-water immersion and Ask A Vet for venom reactions.

🌡️ Care Essentials for Freshwater “Sharks”

• Tank Space: Provide roomy aquaria based on adult size; overcrowding increases aggression.
• Water Quality: Large oxygen-rich tanks, regular 20–30% weekly changes, test ammonia, nitrite (0 ppm), nitrate (<40 ppm), pH 6.5–8.
• Territory & Décor: Include driftwood, rocks, and plants to define spaces and reduce stress.
• Feeding: Balanced omnivorous diets; supplement algae eaters with vegetation wafers.
• Lid: Secure top to prevent jumping out.
• Tankmates: Peaceful mid-to-upper swimmers; avoid fin-nippers or slow species.

🩺 Vet‑Approved 2025 Tips

• Choose species suited to your tank’s volume and stocking goals.
• Plan for adult size—it’s common for juveniles to outgrow their tanks quickly.
• Prioritize stable, clean, oxygenated water from day one.
• Provide hiding zones and watch for fin damage or territorial aggression.
• Use Ask A Vet app to upload symptoms, parameters, or tank photos—get tailored advice fast. AquaCare supplements support stress, immunity, and fin health.

🔗 About Ask A Vet Support

The Ask A Vet app gives 24/7 access to aquatic vets for freshwater “shark” inquiries—behavior, condition checks, water concerns, or aggression issues. We also offer AquaCare supplements tailored to stress support, water stabilization, and fin health. Keep your shark tank safe and thriving in 2025 and beyond! 🐟📲💙