Dotted gizzard shad

Where they come from

Dotted gizzard shad (Konosirus punctatus) are coastal fish from East Asia. You see them moving between bays, estuaries, and lower rivers where the water can swing from nearly fresh to fairly salty. That constant change is a big clue about why they can be touchy in aquariums.

They are a schooling, open-water filter-feeder type of fish. If you are picturing a "show fish" that hangs around rocks, forget it. These guys want room to cruise, and they spend most of their time midwater.

Setting up their tank

This is an expert fish mostly because of space, flow, and food, not because the water numbers are mysterious. Think more like setting up for active pelagic fish than a typical brackish community.

• Tank size: big and long. I would not bother under 6 ft length, and bigger is better if you want a stable school.
• Shape matters: long footprint beats tall. They turn fast and spook easily.
• Filtration: heavy. They produce a surprising amount of fine waste, and you will be feeding tiny foods often.
• Flow and oxygen: strong surface agitation and high dissolved oxygen. They act stressed in "still" tanks.
• Lighting: moderate is fine. What matters more is keeping them calm and eating.

For brackish, pick a target salinity and hold it steady. I have had the best luck keeping them in the "estuary" range rather than trying to bounce them around like the wild. A specific gravity around 1.005-1.012 is a sensible starting band, and you can adjust based on how your fish arrived and what tankmates you want.

• Substrate: optional. Bare bottom makes it easier to keep water clean and see uneaten micro-foods.
• Decor: keep it minimal and pushed to the sides. Give them a clear racetrack.
• Cycling: do not rush this species. They hate ammonia and nitrite, and they do not forgive new-tank swings.
• Acclimation: slow. Salinity and temperature changes hit them harder than most brackish fish.

What to feed them

This is the make-or-break part. Dotted gizzard shad are not "pellet pigs" right out of the bag. They are built to pick at tiny plankton and suspended foods all day. If you only offer big chunks twice a day, they slowly fade even if they look like they are "trying."

• Best staples: enriched baby brine shrimp, copepods, small daphnia (if they will take it in brackish), finely minced mysis, and quality micro-pellets once trained.
• What usually works for training: start with live or moving foods, then mix in frozen finely shaved foods, then dust in micro-pellets so they accidentally take them.
• Feeding rhythm: small amounts, many times. 3-6 feedings a day is not crazy for this fish.
• Vitamins: worth using on frozen foods. They can look "fine" until they suddenly do not.

Be ready for messy feeding. Tiny foods spread everywhere, so you will be leaning on mechanical filtration, frequent rinsing of filter socks/sponges, and regular water changes. I like to siphon the bottom after heavier feed days, especially in bare-bottom setups.

How they behave and who they get along with

They are a schooling fish, and you will see a big difference between a nervous, skittish group and a calm, confident one. Singles or pairs tend to act like they are always on edge. In a decent-sized group, they settle in and cruise.

• Group size: aim for a real school, not a token pair. More fish spreads out stress.
• Temperament: peaceful, but easily intimidated by pushy feeders.
• Activity: constant midwater movement. Plan tankmates around that.
• Spooking triggers: sudden lights on/off, tapping the glass, fast netting, aggressive tankmates, and shadows overhead.

Tankmates should be calm, non-nippy, and not so predatory that they turn the shad into permanent victims. Also think about feeding competition: if you keep them with fast, aggressive eaters, the shad will lose weight even though food is going in.

Breeding tips

Breeding them in home aquariums is basically a long shot. In the wild they spawn in seasonal cycles with big environmental cues (temperature, salinity shifts, food blooms) and they are used to massive open water. Getting adults to condition is hard, and raising planktonic larvae is a whole separate level.

• If you want to try anyway: start with a large group, not a pair.
• Feed heavy on live and enriched foods for conditioning.
• Simulate seasons slowly: gradual temp and salinity changes over weeks, not days.
• Have rotifers/copepod cultures ready before you see any spawning behavior.

Common problems to watch for

• Starvation in plain sight: they "eat" but lose weight because foods are too big or feedings are too few.
• Spooking and injury: nose scrapes, split fins, and sudden deaths after a panic sprint.
• Oxygen stress: hanging near the surface, rapid breathing, especially after heavy feeding or warm days.
• Water quality spirals: frequent micro-feeding can blow up nitrates and organics fast.
• Parasites on new imports: flashing, excess slime, clamped fins, refusal to eat.

If they stop eating, do not just keep tossing in more food and hoping. First check oxygen and flow, then test for ammonia/nitrite, then look at salinity and temperature stability. After that, think parasites. Quarantine and observation pays off with this species more than most.