From the Tank Log
A reference for the small, the shoaling,
and the quietly territorial.
Identification, husbandry, and water-chemistry guides for the freshwater fish you can actually keep — Cichlidae, Characidae, Poeciliidae, Siluriformes, and the rest of the families that live below the surface of the average home aquarium. Written by an ichthyologist with thirty years of planted-tank records.
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From the tank log
Why Are My Snails Climbing Out of the Tank?
Aquarium snails climb out because of poor water quality, low oxygen, food shortages, stress, or normal exploring. Use this checklist to find the cause and keep snails safely in the tank.
Amano Shrimp vs Nerite Snail for Algae
Compare Amano shrimp and nerite snails for algae control: what each eats, tank size, care needs, compatibility, and when using both is the best choice.
Why Are My Tiger Barbs Attacking Each Other?
Tiger barb aggression inside the shoal almost always means the group is too small. Here is how to identify the type of conflict, fix shoal size and sex ratio, and choose tankmates that do not attract nipping.
Why Is My Cory Catfish Gasping at the Surface?
Corydoras do breathe air through the hindgut, so some surfacing is normal. Here is how to tell a healthy gulp from a genuine oxygen or water-quality emergency.
Why Is My Shrimp Dying After Molting?
Shrimp dying after molting usually means low GH, a TDS swing after a water change, or copper. What the white ring of death looks like and how to stop the losses.
Why Are My Stem Plants Growing Leggy?
Leggy stem plants — long internodes, sparse leaves, stretched growth — are etiolation, a photoreceptor-driven response to insufficient PAR, wrong spectrum, or short photoperiod.
Why Is My Fish Swimming Sideways?
A fish swimming sideways signals anything from constipation in a fancy goldfish to terminal neurological collapse. Identify the presentation type and test water before attempting any treatment.
Why Won't My Fish Eat?
Feeding refusal in aquarium fish ranges from normal post-transport stress to early-stage disease. Covers ten causes, acute vs chronic timelines, and targeted fixes.
Why Won't My Aquarium Cycle?
A stuck aquarium cycle almost always traces to one of four chemistry problems: pH or KH too low, ammonia source wrong, temperature too cold, or something actively killing the bacteria. Identify which nitrogen step is stalled, then fix the root cause.
Why Is My Fish Hiding All the Time?
Fish hiding in aquariums can signal stress, illness, aggression, or nothing at all — correct diagnosis turns on species, timing, and water chemistry. A triage guide for freshwater keepers.
Why Is My Aquarium Water Yellow?
Yellow aquarium water is almost always tannin staining from driftwood or botanicals — harmless and often desirable — or dissolved organic carbon from infrequent maintenance, which is not.
Why Is My Aquarium pH Dropping?
Falling aquarium pH traces to KH exhaustion, heavy bioload, CO2 overdose, or skipped water changes. Identify the cause and fix it without pH-adjusting products.
Canister vs Sump for Large Aquariums
Canister filters and sump systems solve large-tank filtration differently. Canisters are sealed, proven, and hidden; sumps offer far greater media volume and easier maintenance for tanks above 400 litres.
How to Prevent Ich Outbreaks
Ich prevention works because *Ichthyophthirius multifiliis* has a brief free-swimming stage that must find a host within hours or die. Quarantine, stable temperature, and careful sourcing keep it out of the display.
How to Prevent Fish Jumping Out
Three overlapping layers of prevention stop fish from leaving the tank: a close-fitting lid with every cutout sealed, stable water chemistry that removes the urge to flee, and species awareness before you buy.
Why Is My Fish Scratching on Decor?
Fish scratching on decor — called flashing or glancing — signals ectoparasites or water-chemistry irritation. Diagnose by accompanying signs, affected species, recent events, and a water test before medicating.
Why Are My Fish Jumping Out of the Tank?
Fish jumping out of the tank is either species-natural behaviour or an escape response to water-quality failure. Identifying which takes two minutes; not identifying it costs you a fish.
Why Is My Aquarium Water Suddenly Cold?
A sudden drop in aquarium temperature is a 24-hour emergency for tropical fish. Heater failure is the most common cause, but cold water changes, power outages, and room temperature drops all produce the same result.
How to Prevent Ammonia Spikes in New Tanks
Ammonia spikes in new tanks are a setup problem, not bad luck. Completing the nitrogen cycle before stocking, seeding the filter with mature media, and adding fish slowly keeps ammonia at zero from day one.
Why Does My New Aquarium Smell?
Aquarium smell is a diagnostic tool — rotten egg means hydrogen sulphide from anaerobic substrate (urgent); earthy or musty means cyanobacteria; fishy means dead matter or overfeeding; a sharp chemical edge means an uncycled tank with detectable ammonia.
Why Are My Neon Tetras Dying One by One?
Neon tetras dying one by one usually signals Neon Tetra Disease, farm-bred line collapse, or chronic water-chemistry stress. Here is how to tell the difference and what to do.
Cardinal Tetra vs Neon Tetra
Cardinal and neon tetras are routinely confused at the point of sale. They differ in colour pattern, hardiness, water requirements, and origin — this comparison settles which belongs in your tank.
Why Are My Tetras Nipping Fins?
Fin nipping in tetras has two root causes: species selection and shoal size. This guide identifies the confirmed culprits, explains the shoal-size threshold, and gives practical fixes for community tanks.
Why Does My Clown Loach Keep Getting Ich?
Clown loaches get ich repeatedly because they're scaleless, stress easily in groups under five, and need 27–30 °C to maintain immune function. Here's how to break the cycle.
Complete Guides
Pillars for every family
The Complete Livebearers Guide: Guppies, Mollies & More
Field reference to livebearing aquarium fishes: Poeciliidae biology, internal fertilisation, hard-water husbandry, hybridisation, disease.
The Complete Shrimp & Snails Guide: Freshwater Invertebrates
Field reference to freshwater aquarium shrimp and snails: taxonomy, identification, water chemistry, moulting, copper sensitivity, bioload.
The Complete Tetras Guide (Characidae): Schooling & Care
Scientific and practical reference to aquarium tetras: taxonomy, identification, true schooling versus shoaling, blackwater chemistry, disease.
The Complete Barbs Guide (Cyprinidae): Shoals & Care
Scientific and practical reference to aquarium barbs: modern Cyprinidae taxonomy, barbel anatomy, shoaling behaviour, water chemistry.
The Complete Rasboras & Danios Guide: Danionidae Care
Reference guide to rasboras and danios: Danionidae taxonomy, blackwater chemistry, shoaling behaviour, nano species, and aquarium husbandry.
The Complete Cichlids Guide: African, Neotropical & Dwarf Species
Field reference to Cichlidae: taxonomy, identification, water chemistry, breeding modes, social systems.
The Complete Gouramis & Bettas Guide: Labyrinth Fish Care
Reference guide to anabantoid labyrinth fishes: gourami and betta taxonomy, air-breathing anatomy, breeding modes, blackwater chemistry, and aquarium husbandry.
The Complete Catfish Guide: Corydoras, Plecos & Synodontis
Field reference to Siluriformes in aquaria: corydoras, plecos, otocinclus, synodontis, glass catfish, pictus catfish, and practical husbandry.