Tom Coon's orestias

Where they come from

Tom Coon's orestias (Orestias tomcooni) is one of those fish that makes you realize how weird and cool isolated lakes can be. These guys come from the high Andes, in the Lake Titicaca region. Think cold water, big daily temperature swings, intense sunlight, and water chemistry that is not your average community tank.

Setting up their tank

I would not even try these in a brand new tank. They do best in a mature setup where biofilm, microfauna, and the filter bacteria are already settled. They are sensitive in that "nothing is obviously wrong but they waste away" kind of way if the system is too fresh or too swingy.

Temperature is the big one. Aim for cool water and keep it consistent. If your room runs warm, plan on a chiller or at least a proven cooling strategy (cool basement fish room, fan plus open top, seasonal planning).

• Tank size: 20 gallons long is a nice starting point for a small group, bigger is easier
• Temperature: cool water (roughly low-to-mid 60s F is where I have seen them act most natural)
• Filtration: oversized sponge filter or gentle canister with a prefilter sponge (they hate being blasted around)
• Flow: low to moderate, with calm areas
• Oxygen: high - surface agitation helps a lot in cooler setups
• Substrate: sand or fine gravel; they spend time picking at surfaces
• Hardscape: smooth rocks and scattered rubble to break lines of sight
• Plants: optional, but tough cold-tolerant stuff helps (java fern, anubias, mosses, some vallisneria depending on temp)

For water chemistry, I have had the best luck staying away from extremes and focusing on stability and cleanliness. Moderate hardness is usually easier than ultra-soft, but what matters most is that you are not chasing numbers every week. Keep nitrate low, keep detritus from building up, and do smaller, regular water changes.

What to feed them

They are not "dump flakes and forget" fish. The ones I have kept did best with a mix of small live and frozen foods plus some high quality micro pellets. They tend to pick and hunt more than they rush the surface like danios.

• Staples: small sinking pellets, crushed high-protein flakes (sparingly), and frozen cyclops
• Best frozen foods: daphnia, baby brine shrimp, cyclops, finely chopped bloodworms (not as the main diet)
• Live foods (worth the effort): daphnia, grindal worms, microworms, freshly hatched brine shrimp for conditioning
• Occasional: tiny bits of mussel or shrimp, very small amounts

Feed light and watch their bellies. In cool tanks, food rots slower than in warm tanks, but these fish still do not like dirty bottoms. I like two small feedings rather than one big one, and I siphon uneaten bits if they are not gone in a few minutes.

How they behave and who they get along with

Orestias are a little different from typical "schooling" fish. They do better in a small group, but they are not tight schoolers. You will see short spats, posturing, and then they go right back to grazing and cruising.

Tankmates are tricky mostly because of temperature. Most common community fish want it warmer. I keep them species-only or with a very carefully chosen coldwater companion that will not outcompete them at feeding time.

• Best approach: species-only group
• If you must add tankmates: pick cool-water, peaceful fish with similar feeding speed (and be ready to separate)
• Avoid: aggressive fin nippers, fast surface hogs, and anything that wants tropical temps

Breeding tips

Breeding is doable, but it is not a случай thing like guppies. The biggest trigger I have seen is a seasonal pattern: slightly cooler water, heavy feeding with live/frozen foods, then a modest water change with fresh cool water. They scatter eggs around plants and fine textures rather than guarding a nest.

• Conditioning: 2-3 weeks of heavier feeding (daphnia, baby brine, cyclops)
• Spawning media: java moss, spawning mops, or dense fine-leaved plants
• Egg safety: move adults out or move eggs out - adults will snack on them
• Fry foods: infusoria first if needed, then microworms and baby brine shrimp
• Patience: growth is slower in cool water, and that is normal

Common problems to watch for

Most issues with this species trace back to three things: temperature creeping up, water quality slipping, or not enough food getting into the fish. They can look "fine" right up until they are not, so you have to pay attention to small changes in behavior.

• Wasting/weight loss: usually food competition, internal parasites, or a too-new tank with not enough natural grazing
• Heat stress: rapid breathing, hanging near the surface, acting jumpy (especially in summer)
• Oxygen dips: gulping at the surface, clustering near filter outflow
• Bloat/constipation: from heavy rich foods without enough variety
• General sensitivity after shipping: they can crash if you rush acclimation or put them into an unstable tank

If you are troubleshooting, start with the boring stuff: confirm actual tank temperature with a reliable thermometer, increase surface agitation, clean mechanical gunk from the filter (without nuking the bio media), and watch them eat. Seeing them take food confidently is one of the best health checks you have.