Freshwater 20-gallon: $10-25/month. Freshwater 75-gallon planted: $30-60/month. Saltwater 30-gallon nano: $50-100/month. Saltwater 75-gallon mixed reef: $80-150/month. Saltwater 180-gallon SPS: $150-350/month. Costs include electricity, salt mix (saltwater), supplements, food, filter media, and fish/coral attrition.
Monthly aquarium costs are dramatically higher than most beginners expect. Equipment is one-time; operating cost is forever.
| Cost line | FW 20gal | FW 75gal | SW 30gal nano | SW 75gal reef |
|---|---|---|---|---|
| Electricity | $5-10 | $15-30 | $15-30 | $25-60 |
| Food | $3-8 | $10-20 | $10-20 | $15-30 |
| Filter media | $2-5 | $5-15 | $5-15 | $10-25 |
| Salt mix | - | - | $10-25 | $20-50 |
| Supplements / dosing | - | - | $10-25 | $15-40 |
| Total monthly | $10-25 | $30-60 | $50-100 | $80-150 |
Excluded: livestock attrition (replacement of dead fish/coral), one-time equipment failures, and any added inventory (new fish, new coral). Plan for $20-50/month additional in livestock spending if you're actively building the tank.