Ninespine Stickleback

Where they come from

Ninespine sticklebacks (Pungitius pungitius) are little northern survivors. You find them across Europe, Asia, and parts of North America in everything from ditches and slow creeks to cold lakes and brackish edges. That background explains a lot: they handle cool water well, they like cover, and they notice everything that moves.

Setting up their tank

Give them a tank that feels like a weedy shoreline, not a bare glass box. They are bold once settled, but they relax way faster if you build in sight breaks and fine-leaved cover.

• Tank size: 15-20 gallons for a small group is a nice starting point. Bigger makes everything easier, especially if you want more than one male.
• Flow: gentle to moderate. They do not need a river blast, but they like clean, oxygenated water.
• Temperature: cool room temps are fine. Think roughly 60-72F as a comfort zone.
• Substrate: sand or fine gravel. They are not big diggers, but sand makes feeding mess easier to manage.
• Hardscape: branches, small stones, and lots of plant thickets so they can duck out of view.
• Plants: hornwort, water sprite, guppy grass, milfoil-type stems, and mosses. Floating plants help too.

Filtration does not need to be fancy. A sponge filter or a small HOB works, as long as you keep the water clear and do regular water changes. The big thing is cover. If the tank looks "too planted" you are usually getting close.

What to feed them

These are micro-predators. Mine ignored flakes for a while and then sort of accepted them, but they really light up for live and frozen foods. If you want good color and calmer behavior, feed like you would for small wild-type fish: lots of variety, small portions, and a little hunting time.

• Frozen: daphnia, cyclops, baby brine shrimp, chopped bloodworms, mysis (small pieces).
• Live (great for conditioning): daphnia, grindal worms, white worms (sparingly), mosquito larvae where legal and safe, live baby brine.
• Dry: tiny sinking pellets or micro-granules. Flake works better if you crush it and pre-soak it so it sinks.

How they behave and who they get along with

They are curious, a little spicy, and surprisingly aware of you. In a group they do a lot of posturing and quick chases, especially as males start thinking about nesting. Most of it is bluffing, but cramped tanks make it real.

Tankmates are where people get tripped up. They are not community fish in the "toss them in with anything" sense. They can nip fins, they will hunt tiny shrimp and fry, and slow long-finned fish are basically asking for trouble.

• Best setup: species-only group with lots of plants and some floating cover.
• Possible tankmates (if the tank is roomy): fast, short-finned coolwater fish that can handle themselves, like some small minnows/danios, and tougher bottom fish like weather loaches in larger tanks.
• Avoid: guppies/long-fins, fancy bettas, slow gouramis, small shrimp, and tiny fry you actually want to keep.

Breeding tips

Breeding is honestly one of the coolest parts of keeping them. The male builds a little nest in plants, courts the female, and then guards the eggs and wrigglers. If you have ever kept three-spined sticklebacks, the vibe is similar, just smaller and often a bit sneakier.

• Conditioning: lots of live/frozen foods for a couple weeks and keep the water clean.
• Nest materials: fine-leaved plants and moss. They like something they can stitch together.
• Spawning setup: a dedicated tank makes life easier, or at least a heavily planted section where the male can hold a territory.
• After spawning: the male may guard well, but other sticklebacks will eat eggs/fry if they get a chance. If you want numbers, move the female out, or pull the nest to a rearing tank with gentle aeration.
• First foods: infusoria/rotifers for the first days, then baby brine shrimp and microworms as they grow.

Common problems to watch for

Most issues I have seen with ninespines come from mismatched expectations: keeping them too warm, too bare, or with the wrong roommates. They are hardy in a "tough little wild fish" way, but they still react badly to chronic stress.

• Fin nipping and torn fins: usually tankmate-related or not enough space/cover. Add plants, reduce stocking, or go species-only.
• Not eating prepared foods: start with frozen daphnia/cyclops, then mix in crushed pellets. Once one learns, the rest often follow.
• Bloating/constipation: ease off rich foods, add daphnia, and do smaller feedings.
• Hiding and washed-out color: too bright, too open, or too much chasing. Floating plants and more hard breaks fix this fast.
• Sudden losses after a big water change: they can be sensitive to large swings. Match temperature and do smaller, more frequent changes.