# Sakana Fugu-Ultra vs Spark-X2.6-4B

> Side-by-side benchmark comparison for Sakana Fugu-Ultra and Spark-X2.6-4B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/sakana-fugu-ultra-vs-spark-x2-6-4b
- Last updated: October 20, 2026

- Shared sourced benchmarks: 5
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Sakana Fugu-Ultra leads by point estimate. Conditional score ranges do not establish rank confidence. Choose using the category evidence and your own workload tests.

## Summary

- Sakana Fugu-Ultra has the higher overall point estimate 77 to 40.14. Conditional score ranges do not establish rank confidence.
- The clearest category separation is in reasoning, where the averages are 83.5 for Sakana Fugu-Ultra and 48.8 for Spark-X2.6-4B.
- The biggest single benchmark swing is HLE w/o tools in Knowledge, with scores of 50% and 17.9%.
- Spark-X2.6-4B is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Sakana Fugu-Ultra | Spark-X2.6-4B |
|----------|----------|----------|
| Creator | Sakana AI | SparkLLM |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Overall Score | null | 40.14 |
| Benchmarks Covered | 11 | 20 |
| Pricing (input/output) | Pricing unavailable / Pricing unavailable | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 33 (Estimated · #89/131)

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 82.1% | Coming soon | Coming soon |
| BFCL v4 | Coming soon | 71.8% | Coming soon |
| τ²-bench results | Coming soon | 86.9% | Coming soon |
| MCP Atlas | Coming soon | 62.4% | Coming soon |
| BrowseComp | Coming soon | 53.1% | Coming soon |
| HLE w/ tools | Coming soon | 36.9% | Coming soon |
| τ³-bench results | Coming soon | 34.7% | Coming soon |
| Claw-Eval | Coming soon | 69.9% | Coming soon |

### Coding

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 30.6 (Estimated · #95/152)

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Pro | 73.7% | 54.3% | Sakana Fugu-Ultra |
| Terminal-Bench 2.1 | 82.1% | Coming soon | Coming soon |
| LiveCodeBench v6 | 93.2% | Coming soon | Coming soon |
| LiveCodeBench Pro | 90.8% | Coming soon | Coming soon |
| SciCode | 58.7% | 36.8% | Sakana Fugu-Ultra |
| SWE-bench Verified | Coming soon | 62.8% | Coming soon |
| SWE Multilingual | Coming soon | 64.7% | Coming soon |

### Reasoning

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: 83.5 (Unranked · 1 rankable row)
- Spark-X2.6-4B public-lane score: 48.8 (Unranked · 2 rankable rows)

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| MRCRv2 | 93.6% | Coming soon | Coming soon |
| LongBench v2 | Coming soon | 53.3% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: 77.1 (Unranked · 1 rankable row)
- Spark-X2.6-4B public-lane score: Coming soon

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | 86.6% | Coming soon | Coming soon |

### Knowledge

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 43 (Estimated · #109/187)

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 95.5% | 69.9% | Sakana Fugu-Ultra |
| GPQA-D | 95.5% | 77.1% | Sakana Fugu-Ultra |
| HLE w/o tools | 50% | 17.9% | Sakana Fugu-Ultra |

### Instruction Following

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 78.2 (#62/149)

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| IFEval | Coming soon | 93.6% | Coming soon |
| IFBench | Coming soon | 75.8% | Coming soon |

### Mathematics

- Winner: Not comparable
- Sakana Fugu-Ultra public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 76.4 (Unranked · 3 rankable rows)

| Benchmark | Sakana Fugu-Ultra | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| AIME26 | Coming soon | 91.2% | Coming soon |
| HMMT Feb 2026 | Coming soon | 81.3% | Coming soon |
| IMOAnswerBench | Coming soon | 75.2% | Coming soon |

## FAQ

### Which is better overall, Sakana Fugu-Ultra or Spark-X2.6-4B?

Sakana Fugu-Ultra has the higher overall point estimate. Conditional score ranges do not establish rank confidence.

### Where is the biggest gap between Sakana Fugu-Ultra and Spark-X2.6-4B?

The widest category gap is in reasoning, where the averages are 83.5 for Sakana Fugu-Ultra and 48.8 for Spark-X2.6-4B.

### How many benchmarks does Sakana Fugu-Ultra cover on BenchLM?

Sakana Fugu-Ultra currently has 11 sourced benchmark scores on BenchLM.

### How many benchmarks does Spark-X2.6-4B cover on BenchLM?

Spark-X2.6-4B currently has 20 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Sakana Fugu-Ultra vs Sakana Fugu](/compare/sakana-fugu-vs-sakana-fugu-ultra)
- [Spark-X2.6-4B vs Sakana Fugu](/compare/sakana-fugu-vs-spark-x2-6-4b)
- [Sakana Fugu-Ultra vs Fugu Cyber](/compare/sakana-fugu-cyber-vs-sakana-fugu-ultra)
- [Spark-X2.6-4B vs Fugu Cyber](/compare/sakana-fugu-cyber-vs-spark-x2-6-4b)

## Explore More

- [Sakana Fugu-Ultra profile](/models/sakana-fugu-ultra)
- [Spark-X2.6-4B profile](/models/spark-x2-6-4b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)