Pet & Aquarium Trade: how released pets and aquatic plants become invasive species

The pet and aquarium trade is a major pathway for aquatic and non-aquatic invasions, moving fish, snails, reptiles, amphibians, birds, crustaceans, and ornamental plants far beyond their native ranges. When unwanted pets are released or aquarium plants are dumped into waterways, they can establish fast-growing populations that outcompete native species and disrupt entire ecosystems (USFWS 2023).

"Most aquatic invasions begin with a single release."

— Texas Parks & Wildlife Department, 2024

How this pathway works

The mechanisms behind pet-trade invasions are well-documented and surprisingly consistent:

• Released pets — Goldfish, red-eared sliders, iguanas, and pythons are frequently released when they become too large, aggressive, or expensive to care for (USGS 2023).
• Dumped aquarium plants — Popular aquarium plants like hydrilla, parrot feather, and Brazilian waterweed spread rapidly when introduced into lakes and streams (USDA APHIS 2023).
• Snails, shrimp & invertebrates — Apple snails, mystery snails, and invasive shrimp species often hitchhike in aquarium plant shipments and are introduced when tanks are cleaned out.
• Pathogens & parasites — Aquarium water can contain diseases such as koi herpesvirus, chytrid fungus, or parasites that infect native fish and amphibians (NOAA 2024).
• Outdoor ponds & water gardens — Koi ponds, backyard water features, and ornamental lilies can overflow during storms, sending non-native species directly into natural waterways.

Why this vector matters

Pet trade species are uniquely dangerous as invaders. They are already adapted to captivity, making them hardy and tolerant of varied conditions. They are often long-lived, increasing the chance of establishment. They are frequently released in groups, boosting survival odds. And they are sold nationwide, creating repeated introduction points across the country.

High-risk species & groups

These categories consistently lead to new invasions — many reproduce quickly, tolerate poor water quality, and have no natural predators in their introduced ranges:

What reduces risk

These practices are simple, scalable, and highly effective at reducing pet-trade-driven invasions:

• Don't Let It Loose — The national campaign urging pet owners never to release animals or plants into the wild; the single most impactful behavior change available (USFWS 2023).
• Surrender events — Many states host amnesty days where owners can turn in unwanted exotic pets safely and without penalty.
• Freeze or dry aquarium plants before disposal to prevent regrowth in drains or waterways.
• Disinfect aquarium water before pouring it down drains to kill pathogens and larvae.
• Choose native or non-invasive species for outdoor ponds and water gardens.
• Secure outdoor ponds to prevent overflow and species escape during storms.

Texas spotlight: pet-trade species of concern

Texas has several high-risk species linked directly to the pet and aquarium trade, many now established in Texas waterways:

• Apple snails — Now established in multiple Texas watersheds, feeding on native aquatic vegetation (TPWD 2024).
• Plecostomus catfish — Burrow into riverbanks, destabilizing shorelines and degrading habitat for native species.
• Red-eared sliders — Outcompete native turtles for basking sites; widely released from the pet trade across the state.
• Giant salvinia — Frequently spread through aquarium and water garden dumping; capable of blanketing water surfaces and eliminating oxygen for native aquatic life.
• Marbled crayfish — A self-cloning species capable of explosive population growth from a single individual.